We are delighted to contribute to this special issue honoring the work of Anna Costanza Baldry, who was a doctoral student of David Farrington in the 1990s. We have had the privilege of collaborating with Anna to study many topics, including the effectiveness of interventions to tackle bullying (Ttofi et al. 2008; 2010) and cyberbullying (Baldry et al. 2018; Sorrentino et al. 2018), the overlap between bullying and cyberbullying (Baldry et al. 2017), the epidemiology of cyberbullying in Europe (Sorrentino et al. 2019), risk factors for bullying (Baldry and Farrington 1998; Baldry and Farrington 2010), protective factors against bullying (Baldry and Farrington 2005), and risk factors for cyberbullying (Baldry et al. 2015; Zych et al., 2019a.

Violence, in all its different manifestations, is a universal problem affecting the lives of millions of individuals across the world (Krug et al. 2002). It is a complex multifaceted phenomenon that transcends social (Zietz et al. 2020), economic (Font and Maguire-Jack 2020; Reichel 2017), and geographic borders (Barter et al. 2017; Mesman et al. 2020). Beyond its negative implications for physical health (Skinner et al. 2020) and mental health (Lagdon et al. 2014), violence also impacts societies at the financial level (Wickramasekera et al. 2015). A recent international review of interpersonal violence --defined as violence between family members and intimates, and violence between acquaintances and strangers that is not intended to further the aims of any formally defined group or cause-- provides clear evidence of the financial costs of violence for societies across the world, with US estimates reaching 3.3% of GDP (Waters et al. 2005).

Child maltreatment within the family, in all its varying severity levels, is particularly damaging, because of the betrayal of supposed close relationships of trust within that environment (Malloy et al. 2014; Morrison et al. 2018). Child abuse and neglect are often seen as subdivisions of the overarching umbrella of child maltreatment, which includes both acts of commission (i.e. physical, emotional and/or abuse) and acts of omission (i.e. neglect; Del Vecchio et al. 2018). Using the National Child Abuse and Neglect Data System Child Files (2003–2014) and Census data to develop synthetic life tables of the cumulative prevalence of reported childhood maltreatment in the US, Kim et al. (2017) estimated that 37.4% of all American children experienced a child protective services investigation by age 18. In the United Kingdom, the Crime Survey for England and Wales (CSEW) estimated that one in five adults aged 18 to 74 (a total of 8.5 million people) had experienced at least one form of child abuse, including emotional abuse, physical abuse, sexual abuse, or witnessing domestic violence or abuse, before the age of 16 (Office for National Statistics 2020). Research shows that children who experience maltreatment rarely experience only one type, likely causing compounding effects (Zeanah and Humphreys 2018).

This special issue provides up-to-date evidence on the linkage between family violence and youth violence within school and community settings. It brings together a wealth of unique data, both cross-sectional and longitudinal, a plethora of data collection methods (based on self-reported interviews, observations, and officially recorded data) and sensitive modes of analyses to examine issues of violence from multidisciplinary perspectives, including developmental psychology, social work, criminology and criminal justice, medicine, and health sciences. With a particular focus on youth populations, these articles seek to understand various forms of family violence, their prevalence and etiology, and their consequences.

School bullying is a very important social problem. For example, large-scale surveys have shown that the prevalence of both perpetration and victimization in the previous month is about one-third of students (Zych et al. 2017). Longitudinal studies have proved that bullying often leads to offending (Ttofi et al. 2011b), violence (Ttofi et al. 2012), and drug use (Ttofi et al. 2016) up to 15 years later. Dating and intimate partner violence (IPV) are also very important social problems, affecting between one-fifth and one-third of young adults (Jennings et al. 2017), and having important negative consequences for health (Copp et al. 2016). The good news is that there are many effective intervention programs for school bullying (Gaffney et al., 2019b), cyberbullying (Gaffney et al., 2019a) and for dating and IPV (Jennings et al. 2017).

In this special issue, particular emphasis is given to providing up-to-date evidence on the impact of child maltreatment across different countries. Based on a stratified random sample of 6233 fourth graders in Taiwan, the study by Hsieh et al. (2020) offers support for the detrimental effect of child maltreatment on internalizing and externalizing problem behavior. Specifically, physical neglect, psychological neglect, physical abuse, psychological abuse, and PTSD were positively related to children’s bullying, after controlling for gender. It was also established that children with higher levels of bullying were likely to report more neglect at home. Anna Baldry also carried out research on the link between school bullying (and cyberbullying) and PTSD (Baldry et al. 2019).

Another study featured in this special issue, by Adams et al. (2020), with a sample of racially and ethnically diverse low-income adolescents from an urban setting in upstate New York, examined the differential associations between maltreatment and suicidal ideation and non-suicidal self-harming behavior, based on adolescent dating violence profiles. Using latent class analyses, Adams et al. (2020) present a three-class model of dating violence: female adolescents without dating violence, those in relationships with mutual verbal abuse, and those in a romantic relationship with multiple and severe forms of dating violence. The effects of child maltreatment on suicidal ideation differed according to adolescent dating violence class membership, with the effects of maltreatment on self-harming behaviors being stronger for females in the multi-subtype victim/perpetrator group.

A positive family environment is crucial for the healthy psychosocial development of children. Healthy family relationships with parents and siblings, and healthy family dynamics more generally, provide ‘behavioral guidelines’ and a nurturing environment for young children (Hoeve et al. 2009). Harsh discipline, for example, in the form of disintegrative/rejecting shaming of a child’s wrongdoing, is significantly associated with a child’s dysfunctional emotion regulation, which in turn is significantly predictive of both sibling aggression within the family and peer aggression within the school (Ttofi and Farrington 2008). Poor family relationships are predictive of long-term maladjustment and life failure. In the Pittsburgh Girls Study (discussed later), negative emotion regulation by parents predicted involvement in dating violence by daughters (Ahonen and Loeber 2016).

Longitudinal data analyses of the Cambridge Study in Delinquent Development (CSDD), which is a prospective longitudinal study of 411 London males, demonstrate the long-term impact of parental conflict and harsh discipline (Farrington et al. 2009). Specifically, harsh parental discipline at ages 8–10 was predictive of persistent offending up to age 50, with 48.4% of persistent offenders having experienced harsh discipline, as opposed to only 24.9% of non-offenders, a statistically significant difference. Similarly, there was a statistically significant difference in the prevalence of individuals who had experienced parental conflict at age 8–10: only 18.2% of non-offenders as opposed to a staggering 35.1% of individuals who persistently offended up to age 50. Later analyses by Farrington and Malvaso (2019) showed that harsh discipline was the most important predictor of violence convictions of the original CSDD males, while parental physical punishment was the second most important predictor of violence convictions of their sons.

Intimate partner violence (IPV) is another form of family violence. While acknowledging the need for continuous revisions to the definitions of IPV (Breiding et al. 2015), this umbrella term refers to threatening or injurious physical, psychological, verbal, or economic behavior directed toward an adult romantic partner, regardless of marital status, and including both ongoing and terminated relationships (Worden 2000). Breiding et al. (2008) utilized data on IPV from over 70,000 respondents of the first-ever administered IPV module within the Behavioral Risk Factor Surveillance System. This was a random-digit-dialed telephone survey, sponsored by the US Centers for Disease Control and Prevention, providing surveillance of health behaviors and health risks among the non-institutionalized adult population of the United States and several US territories. Their results suggest that one in four women and one in seven men reported some form of lifetime IPV victimization. Women experienced significantly higher lifetime and 12-month IPV prevalence, and were more likely to report IPV-related injury than men. IPV prevalence also varied according to state of residence, race/ethnicity, age, income, and education.

In this special issue, based on data from a national sample of 1525 Latino teens and their caregivers, using the Dating Violence among Latino Adolescents Study, Mariscal et al. (2020) identified latent classes of interpersonal victimization and compared these classes on the demographic characteristics, mental health, and delinquency of participants. Their findings indicated a six-class solution: multiform victimization by multiple perpetrators, psychological dating violence victimization, psychological victimization by peers, physical victimization by peers, physical violence victimization by juvenile family members, and uninvolved. Those teens with multiform victimization by multiple perpetrators, and those who were victimized physically and/or stalked by non-family members, scored significantly highest on physical delinquency, lending support to the offender-victim overlap literature (Beckley et al. 2018).

In another study in this special issue, located in four middle schools in the Midwest of the USA, Valido et al. (2020) utilized multi-level within- and between-person longitudinal analyses to test the association between sibling aggression and witnessing family violence on verbal and physical forms of peer aggression. Their study findings lend further support to existing evidence on how aggressive behavior is learned and maintained across contexts in a person’s life (Walters and Espelage 2018). More importantly, they present evidence on explanatory protective variables (such as school belonging) that buffer these associations and which may form the basis for future intervention strategies (Dray et al. 2017; Luthar and Cicchetti 2000). It is important to study protective factors as well as risk factors (e.g. Farrington et al. 2016; Ttofi et al. 2014; Zych et al., 2019a, b, c).

Another study in this special issue, by Perry et al. (2020), based on a sample of 216 mother-infant dyads, examined the complexity of multi-related explanatory factors in the family setting, including maternal aggression, sibling aggression, and environmental risk such as maternal substance use during pregnancy, maternal exposure to violence, and caregiving instability. Their longitudinal path analyses show how environmental risk and child physical aggression in early childhood predicted higher levels of middle childhood caregiver power- assertive discipline, which subsequently predicted lower levels of early adolescent reactive relational aggression.

Contributions in this special issue underscore the importance of evaluating the multiple facets of family violence, family adversity and wider environmental risk when examining the etiology and antecedents of youth violence and victimization, in line with an ecological perspective (Swearer and Doll 2001). Violent youth are quite often also victims of violence (Jennings et al. 2012). Enhancing positive outcomes for troubled children and youth entails addressing their multiple risks and needs (Craig et al. 2017) and adapting service-use towards a positive youth development framework (Sanders et al. 2017), particularly in the case of high-resource-using youth within mental health and criminal justice systems (Whittaker 2009).

In this special issue, two studies address challenges faced by youth involved in the criminal justice system (Mowen and Fisher 2019;Wagers et al. 2020) while another study focuses on referred adolescents within the mental health system (Benton et al. 2020). Based on the the male-only youth subsample of the Serious and Violent Offender Reentry Initiative, Mowen and Fisher (2019) used a series of dynamic panel data models to investigate how family dynamics may simultaneously promote and/or inhibit family violence perpetration among youth undergoing the process of re-entry. Both pre- and post-release levels of family conflicts were significantly related to increased family violence during reintegration, highlighting the pressing need to reduce family conflict among incarcerated and recently released youth to curb family violence perpetration. Parental discord has often been found to be an important predictor of antisocial behavior, for example in the meta-analysis by Derzon (2010), based on 233 reports from 119 longitudinal studies.

In another study in this special issue, based on four waves of data from 808 young men with histories of serious offending, Wagers et al. (2020) explored rates of physical and emotional IPV victimization and perpetration, the offender-victim overlap, and the associations between IPV in young adulthood and early exposure to violence in early adolescence. Their results stress the importance of addressing violence and victimization across different contexts and for different age groups, and how intervening during adolescence is critical to prevent IPV during young adulthood.

There have been a number of studies of IPV and dating violence in the CSDD. Theobald and Farrington (2012) investigated the childhood predictors of male perpetrators of IPV, and found that they included a convicted father, a disrupted family, poor parental supervision, unpopularity, daring, and low verbal intelligence. In adulthood, these males had problems of drinking, drug use and unemployment. Earlier, Lussier et al. (2009) showed how antisocial behavior in adolescence and low verbal intelligence led to IPV at age 48. Theobald et al. 2016b, c) compared risk factors for males who were violent both inside and outside the home with risk factors for males who were only violent in one setting. The generally violent males tended to be worse on psychopathy, personality disorders, and life success. Theobald et al. (2016a) investigated the childhood and adolescent predictors of dating violence committed in their 20s by the male and female children of the original male sample. For the daughters, the most important predictors were a convicted father, parental conflict, large family size, and poor housing. For the sons, the most important predictors were a young mother and father, a disrupted family, truancy, and convictions. Farrington et al. (2017) summarized conclusions from systematic reviews of explanatory risk factors for violence, sex offending, dating violence, and IPV.

Youth violence and antisocial behavior in general has detrimental effects on mental health (Reising et al., 2019b; Ttofi et al. 2011a), and addressing issues of mental health is imperative in both community and clinical samples (Reising et al., 2019a). One study in this special issue, based on a sample of 151 clinically referred adolescents aged 12–18, investigated subgroups of adolescents with varying experiences of maltreatment, bullying perpetration and peer victimization, and explored how subgroups were related to depressive symptoms, hopelessness, and impairment (Benton et al. 2020). Rates of exposure to maltreatment, bullying, and peer victimization were high overall, but the high exposure group reported more severe depressive symptoms, higher levels of hopelessness, and more impairment, and they had worse clinical outcomes overall than the low exposure group.

Addressing the multifaceted interconnections between family, school, and community violence requires careful analyses not only at the micro-level but also at the macro-level. One entry in the special issue offers just that. Using cross-national data collected in almost 200 countries, Narvey et al. (2020) examined the association between women’s rights (based on whether women experience more gender discrimination in economic and family decisions) and overall homicide rates. Using finite mixture modeling, they found that countries with the least gender discrimination had the lowest overall average homicide rate, pointing towards the importance of education for all youth, irrespective of gender, in tackling violence in societies.

Four of the articles in this special issue have analyzed longitudinal data. Prospective longitudinal studies are extremely important in making it possible to draw conclusions about causal effects, because they can establish the time ordering of possible causes and possible effects (see e.g. Farrington 2013; Loeber and Farrington 2008; Murray and Farrington 2010). The article by Valido and colleagues is especially important in comparing results between and within individuals. The concept of a cause requires that within-individual changes in a causal factor are reliably followed by within-individual changes in an outcome. Similarly, prevention and intervention research requires changes within individuals. However, most research in psychology and the social sciences is based on between-individual differences, and conclusions about within-individual changes cannot necessarily be drawn. There have been some previous efforts to compare results between and within individuals (e.g. Farrington et al. 2002; Hemphill et al. 2015), but more within-individual research in longitudinal studies is greatly needed in order to advance knowledge about causes.

Only one of the articles in this special issue (Perry et al. 2020) followed up children over a period of 10 years or more, into adolescence. There is a great need for long-term longitudinal studies with frequent assessments from childhood to adulthood, to advance knowledge about the development of bullying, youth violence, dating violence, and IPV. Jolliffe et al. (2017) reviewed longitudinal studies of community samples of at least 300 persons that started in childhood or early adolescence and followed up to at least age 30, and found only 11 that included measures of official and self-reported offending.

More longitudinal studies are needed like the Pittsburgh Youth Study or PYS (Loeber et al., 2017a and the Pittsburgh Girls Study or PGS (Loeber et al. 2017b). In the PYS, one sample of 503 males was followed up annually from age 7 to age 19, and then up to age 28, while another sample of 506 males was followed up annually from age 13 to age 25, and then up to age 34 (with high retention rates). In the PGS, 2450 females were assessed annually from age 11 to age 19, and subsamples were followed up to age 23. These kinds of studies make it possible to draw convincing conclusions about causes, by studying changes within individuals in influencing factors that are reliably followed by within-individual changes in outcomes. They would permit great advances in knowledge about the development and causes of bullying, youth violence, dating violence, and IPV.

Policy makers, evaluation researchers and practitioners who seek to enhance outcomes for troubled children and youth need to keep in mind the multiple challenges faced by children and youth within their early family environments. The intersection of family violence and youth violence remains a fertile field for further research, and it is important to provide family, school and community services within an ecological focus (Dembo and Walters 2003; Espelage and Swearer 2004). We are very happy to comment that this special issue has greatly advanced knowledge about bullying youth violence, child maltreatment, dating violence, and IPV. Anna Baldry would have been pleased with it, and we hope that it will be widely read.