a b s t r a c tBullying is a common aggressive behaviour in school, with a number of cross-sectional studies showing that it exhibits a high comorbidity with other problem behaviours. The present study aims to estimate the comorbidity of school bullying (perpetration and victimisation) with drug use by incorporating and meta-analysing all available evidence on the cross-sectional association between the two variables. Meta-analytic results are based on a comprehensive systematic review across 20 databases and 46 journals. A total of 61 relevant manuscripts were included in the systematic review. Following explicit methodological criteria for the inclusion/exclusion of reports, 13 of them were eligible for the meta-analysis. The association of school bullying perpetration with drug use (adjusted odds ratio OR = 2.82; 95% CI 1.97-4.02; z = 5.71; p b .001) suggests a very strong relationship. For example, if a quarter of children were bullies and a quarter were drug users, this value of the OR would correspond to 40.88% of bullies being also drug users, compared with 19.71% of non-bullies. The association of school bullying victimisation with drug use (adjusted odds ratio OR = 1.79; 95% CI 1.38-2.32; z = 4.41; p b .001) suggests a moderate relationship. For example, if a quarter of children were victims and a quarter were drug users, this value of the OR would correspond to 33.69% of bullied youth also being drug users, compared with 22.1% of non-bullied youth. Adjusted effect sizes are based on study findings that used statistical controls for confounding variables, thus providing the unique association of school bullying with drug use over and above other important risk factors that may explain this association. Implications for policy and intervention research arising from this review are highlighted.

Weapon carrying has detrimental effects for perpetrators and victims alike. It is therefore imperative that research efforts are invested into establishing those contextual factors that are associated with this antisocial behavior. This systematic and meta-analytic review investigates the association of weapon carrying with bullying perpetration and victimization inside and outside the school context. Results on pure bullies, pure victims and bully-victims are also presented. Further to extensive searches, across 20 databases and 46 journals, and careful screening of reports, in line with pre-established methodological criteria, a total of 35 manuscripts are included in the meta-analysis. Narrative results based on longitudinal studies are also presented but not meta-analyzed given the variability in study characteristics and the small number of studies. Weapon carrying is significantly associated with both bullying perpetration (adjusted OR = 2.64; p <.001) and victimization (adjusted OR = 1.58; p <. 05). Effect sizes are larger when looking at discrete categories of pure bullies (adjusted OR = 3.24; p < 0.01), pure victims (adjusted OR = 1.79; p < 0.05) and bully-victims (adjusted OR =5.66; p < .001) when compared with non-involved school children. Subgroup analyses suggest that pure victims (Q= 6.77; p < .01) and bully-victims (Q = 8.01; p < .01) are significantly more likely to carry a weapon inside than outside the school, thus rendering support to the 'vulnerability/selfprotection' hypothesis. Pure bullies have the same odds of carrying a weapon inside and outside the school context (Q= 0.60; p = .44), supporting a persistent antisocial personality theoretical framework. Implications for policy and practice arising from our results are discussed.

This Campbell systematic review examines the impact of interventions to reduce exclusion from school. School exclusion, also known as suspension in some countries, is a disciplinary sanction imposed by a responsible school authority, in reaction to students' misbehaviour. Exclusion entails the removal of pupils from regular teaching for a period during which they are not allowed to be present in the classroom (in‐school) or on school premises (out‐of‐school). In some extreme cases the student is not allowed to come back to the same school (expulsion). The review summarises findings from 37 reports covering nine different types of intervention. Most studies were from the USA, and the remainder from the UK. Included studies evaluated school‐based interventions or school‐supported interventions to reduce the rates of exclusion. Interventions were implemented in mainstream schools and targeted school‐aged children from four to 18, irrespective of nationality or social background. Only randomised controlled trials are included. The evidence base covers 37 studies. Thirty‐three studies were from the USA, three from the UK, and for one study the country was not clear. School‐based interventions cause a small and significant drop in exclusion rates during the first six months after intervention (on average), but this effect is not sustained. Interventions seemed to be more effective at reducing some types of exclusion such as expulsion and in‐school exclusion. Four intervention types – enhancement of academic skills, counselling, mentoring/monitoring, and skills training for teachers – had significant desirable effects on exclusion. However, the number of studies in each case is low, so this result needs to be treated with caution. There is no impact of the interventions on antisocial behaviour. Variations in effect sizes are not explained by participants' characteristics, the theoretical basis of the interventions, or the quality of the intervention. Independent evaluator teams reported lower effect sizes than research teams who were also involved in the design and/or delivery of the intervention. Plain language summary Interventions can reduce school exclusion but the effect is temporarySome interventions – enhancement of academic skills, counselling, mentoring/monitoring, and skills training for teachers – appear to have significant effects on exclusion. The review in briefInterventions to reduce school exclusion are intended to mitigate the adverse effects of this school sanction. Some approaches, namely those involving enhancement of academic skills, counselling, mentoring/monitoring and those targeting skills training for teachers, have a temporary effect in reducing exclusion. More evaluations are needed to identify the most effective types of intervention; and whether similar effects are also found in different countries. What is this review about?School exclusion is associated with undesirable effects on developmental outcomes. It increases the likelihood of poor academic performance, antisocial behavior, and po...

Transactional sex, the casual exchange of sexual favors for money or gifts, has been associated with negative outcomes and health risks, particularly among youth. This global review of the evidence explores trends of buying and selling sex among the general population of male and female youth across 28 countries. It compares the differences and similarities in prevalence rates between genders (male versus female), sex trading activities (selling versus buying), and country income groups (high-income versus low-and middle-income countries) and examines the relationships and situations surrounding transactional sex, and its correlates. The screening of reports resulted in the inclusion of 37 manuscripts (N = 120,447 participants), involving peer review and grey literature describing longitudinal and cross-sectional research across 7 high-income and 21 low-and middle-income countries. The review of prevalence rates suggests relatively low rates of transactional sex in highincome countries (with selling and buying rates below 10% in all countries) and relatively high, although varying rates, in low-and middle-income countries (with selling and buying rates of 60% or higher in seven countries). Gender disaggregated data suggests that boys are more likely than girls to sell sex in high-income countries while the opposite seems to be true in low-and middle-income countries. The findings suggest that initial contact between sellers and buyers is most often established through friends, acquaintances, and dating websites. The age of onset is around 15 years, many sellers and buyers already know each other before trading sex, and they are often of a similar age. Money is the most commonly used form of compensation. Correlates of selling sex include involvement in other risky sexual behaviors, substance use, infection with sexually transmitted diseases, mental health problems, family break-up, and a history of victimization. No or mixed relations have been found with socioeconomic and educational status. The correlates of buying sex include promiscuity, substance use, violence perpetration and, to some extent, higher socioeconomic status. Recommendations for future research are discussed.