Ciations. In order to reduce the volume of results, the presentation is focused on the four configurations of GS-5816 biological activity delinquency that were associated with gang participation (see again Table 3). Time dimensions–Gang participation and multi-type delinquency were limited to adolescence, often with variation across subgroups (details shown in Figures S1 to S3 of the online supporting information). Multi-type delinquency peaked at about age 15 for theft and BAY1217389 site violence (for all youth), about age 17 for combining all three types of serious delinquency (for the youngest cohort), at about age 19 for combined drug sales and serious violence (for all youth), and at about age 19 for combining all three types of serious delinquency (for the oldest cohort). In contrast, specialization in serious violence started out at its highest level in late childhood and then declined steadily across adolescence. Gang participation peaked around age 16, but only among youth living with just one or neither biological parent; the chances of joining a gang did not vary significantly by age for boys living with both biological parents. Generally, historical time was unrelated to youth’s chances of engaging in multi-type delinquency (see again Table 4). However, the expected peak in the middle 1990s was evident for gang membership among youth whose parents had less than a high school education. For boys whose parents had a high school education or some college education, the chances of participating in a gang were statistically equivalent in early and middle 1990s, but dropped significantly during the late 1990s and early 2000s. Additionally, boys’ chances of combining drug sales with violence also showed the expected peak at mid-NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptJ Res Adolesc. Author manuscript; available in PMC 2015 June 01.Gordon et al.Pagedecade, but only among boys who were ever in a gang. Among boys who were never in a gang, the chances of combining drug sales with violence were much lower overall, and increased slightly across the decade. In addition to moderation of youth’s age with cohort discussed above, historical period moderated developmental trends in combining all three types of serious delinquency. The mid-adolescence peak in this delinquency combination was evident only in the early and middle 1990s; boys’ chances of engaging in all three types of delinquency were much lower in the late 1990s and early 2000s. In addition to moderation by cohort, we found a main effect for cohort in predicting youth’s chances of specializing in violence, with the oldest cohort exhibiting higher levels. The two cohorts also had similar levels of gang participation in the early and middle 1990s, but the youngest cohort had higher levels in the late 1990s and early 2000s. Common covariates–Table 4 shows that residential mobility and race significantly predicted both serious delinquency configurations and active gang membership. Similar patterns of associations occurred for gang participation and for the two delinquency outcomes most associated with gang membership: drug selling along with serious violence and all three types of serious delinquency. For each outcome, having moved in the prior year elevated the probability of engaging in the activities. In contrast, residential mobility was not significantly associated with the chances that boys would specialize in serious violence or combine serious theft and serious violence. Race was ass.Ciations. In order to reduce the volume of results, the presentation is focused on the four configurations of delinquency that were associated with gang participation (see again Table 3). Time dimensions–Gang participation and multi-type delinquency were limited to adolescence, often with variation across subgroups (details shown in Figures S1 to S3 of the online supporting information). Multi-type delinquency peaked at about age 15 for theft and violence (for all youth), about age 17 for combining all three types of serious delinquency (for the youngest cohort), at about age 19 for combined drug sales and serious violence (for all youth), and at about age 19 for combining all three types of serious delinquency (for the oldest cohort). In contrast, specialization in serious violence started out at its highest level in late childhood and then declined steadily across adolescence. Gang participation peaked around age 16, but only among youth living with just one or neither biological parent; the chances of joining a gang did not vary significantly by age for boys living with both biological parents. Generally, historical time was unrelated to youth’s chances of engaging in multi-type delinquency (see again Table 4). However, the expected peak in the middle 1990s was evident for gang membership among youth whose parents had less than a high school education. For boys whose parents had a high school education or some college education, the chances of participating in a gang were statistically equivalent in early and middle 1990s, but dropped significantly during the late 1990s and early 2000s. Additionally, boys’ chances of combining drug sales with violence also showed the expected peak at mid-NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptJ Res Adolesc. Author manuscript; available in PMC 2015 June 01.Gordon et al.Pagedecade, but only among boys who were ever in a gang. Among boys who were never in a gang, the chances of combining drug sales with violence were much lower overall, and increased slightly across the decade. In addition to moderation of youth’s age with cohort discussed above, historical period moderated developmental trends in combining all three types of serious delinquency. The mid-adolescence peak in this delinquency combination was evident only in the early and middle 1990s; boys’ chances of engaging in all three types of delinquency were much lower in the late 1990s and early 2000s. In addition to moderation by cohort, we found a main effect for cohort in predicting youth’s chances of specializing in violence, with the oldest cohort exhibiting higher levels. The two cohorts also had similar levels of gang participation in the early and middle 1990s, but the youngest cohort had higher levels in the late 1990s and early 2000s. Common covariates–Table 4 shows that residential mobility and race significantly predicted both serious delinquency configurations and active gang membership. Similar patterns of associations occurred for gang participation and for the two delinquency outcomes most associated with gang membership: drug selling along with serious violence and all three types of serious delinquency. For each outcome, having moved in the prior year elevated the probability of engaging in the activities. In contrast, residential mobility was not significantly associated with the chances that boys would specialize in serious violence or combine serious theft and serious violence. Race was ass.