Ng-delinquency association might vary between the cohorts as well. We specified our models to test for such moderation. To justify combining the two cohorts together in a single analysis, we also tested for moderation by cohort in the association of covariates with gang activity and with serious delinquency patterns. We describe these models in the Method section. Current study This paper contributes to the existing developmental literature by documenting the extent to which young men’s gang membership coincides with three aspects of serious delinquency and by testing whether similar risk and protective factors are associated with certain configurations of delinquency and gang involvement. We consider two novel research questions. First, we examine what combinations of serious delinquent acts (drug sales, serious theft, serious violence) are more likely among gang members versus non-gang involved youth. We sharpen the comparison beyond prior studies by focusing on young men who ever engaged in serious delinquency over the course of the study. We hypothesize that gang members’ delinquency patterns would be concentrated within several types, because other research suggests that some gangs are strictly territorial (and may promote only violence), whereas others engage in drug trafficking (and thus members may deal drugs and brandish weapons in order to protect drug territory), and others are broadly immersed in crime (and may not only deal drugs but also stolen goods, and may use violence to control both markets). Secondly, we consider what background characteristics associate with youth’s chances of engaging in these sets of serious delinquent acts, and, we test whether these correlates are similar for gang and non-gang involved youth.NIH-PA Author Manuscript NIH-PA Author Manuscript MethodSampleNIH-PA Author ManuscriptWe used longitudinal data from the PYS. Participants were initially selected from a list of boys provided by the Pittsburgh Board of Education in 1987 (Loeber et al., 1998; Loeber et al., 2008). Approximately 84 of eligible boys initially participated, and at least 70 of youth were interviewed at all of the follow-up time points (Loeber et al., 2008). We applied sampling weights to adjust for the study’s oversampling of boys at risk of delinquency. The majority of boys were Black (62 ) and of lower socio-economic status (12 of parents had less than a high school degree, 62 only a high school degree, and 26 some college or a college degree; 22 of youth lived with both of their biological parents).J Res Adolesc. Author manuscript; available in PMC 2015 June 01.Gordon et al.PageTable 1 provides the developmental and historical timing of the study and indicates the waves that we focused on from the full PYS study. In particular, we included two cohorts, boys who were in the first and seventh grades at screening (youngest and oldest cohorts, respectively), because the middle cohort was followed infrequently due to funding restrictions. For the youngest and oldest cohorts, we included 10 annual study waves in which the youth reported their gang participation and engagement in serious delinquency in the prior 12 Carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone cost months (since the last interview) based on the same Crotaline custom synthesis questions (see Table S1 in the online supporting information). This common set of questions began about 4 years after the start of the full PYS study. For clarity, we refer to the first two PYS study waves (the screening wave and first full data collection point, wh.Ng-delinquency association might vary between the cohorts as well. We specified our models to test for such moderation. To justify combining the two cohorts together in a single analysis, we also tested for moderation by cohort in the association of covariates with gang activity and with serious delinquency patterns. We describe these models in the Method section. Current study This paper contributes to the existing developmental literature by documenting the extent to which young men’s gang membership coincides with three aspects of serious delinquency and by testing whether similar risk and protective factors are associated with certain configurations of delinquency and gang involvement. We consider two novel research questions. First, we examine what combinations of serious delinquent acts (drug sales, serious theft, serious violence) are more likely among gang members versus non-gang involved youth. We sharpen the comparison beyond prior studies by focusing on young men who ever engaged in serious delinquency over the course of the study. We hypothesize that gang members’ delinquency patterns would be concentrated within several types, because other research suggests that some gangs are strictly territorial (and may promote only violence), whereas others engage in drug trafficking (and thus members may deal drugs and brandish weapons in order to protect drug territory), and others are broadly immersed in crime (and may not only deal drugs but also stolen goods, and may use violence to control both markets). Secondly, we consider what background characteristics associate with youth’s chances of engaging in these sets of serious delinquent acts, and, we test whether these correlates are similar for gang and non-gang involved youth.NIH-PA Author Manuscript NIH-PA Author Manuscript MethodSampleNIH-PA Author ManuscriptWe used longitudinal data from the PYS. Participants were initially selected from a list of boys provided by the Pittsburgh Board of Education in 1987 (Loeber et al., 1998; Loeber et al., 2008). Approximately 84 of eligible boys initially participated, and at least 70 of youth were interviewed at all of the follow-up time points (Loeber et al., 2008). We applied sampling weights to adjust for the study’s oversampling of boys at risk of delinquency. The majority of boys were Black (62 ) and of lower socio-economic status (12 of parents had less than a high school degree, 62 only a high school degree, and 26 some college or a college degree; 22 of youth lived with both of their biological parents).J Res Adolesc. Author manuscript; available in PMC 2015 June 01.Gordon et al.PageTable 1 provides the developmental and historical timing of the study and indicates the waves that we focused on from the full PYS study. In particular, we included two cohorts, boys who were in the first and seventh grades at screening (youngest and oldest cohorts, respectively), because the middle cohort was followed infrequently due to funding restrictions. For the youngest and oldest cohorts, we included 10 annual study waves in which the youth reported their gang participation and engagement in serious delinquency in the prior 12 months (since the last interview) based on the same questions (see Table S1 in the online supporting information). This common set of questions began about 4 years after the start of the full PYS study. For clarity, we refer to the first two PYS study waves (the screening wave and first full data collection point, wh.