Multivariate analysis of variance was used to test whether pubertal timing was associated with levels of substance use and reports of parent-child relationship quality for girls and boys, respectively. Several differences were found in levels of substance use as a function of pubertal timing (see Table 2 for means and standard errors by group). Simple effects tests using the Bonferroni correction indicated that early maturing boys and girls had higher rates of cigarette and alcohol use at Time 1 compared to their on-time and late maturing counterparts (boys: F (2, 1200) = 14.90 & 14.04, p<.05, partial η2 =.02 for cigarette and alcohol use respectively; girls: F (2, 1331) = 7.93 & 14.41, p<.05, partial η2 =.01 & .02 for cigarette and alcohol use respectively). At Time 2, differences were also found among the groups for levels of substance use (boys cigarette use: F (2, 1200) = 3.60, p<.05, partial η2 =.01; alcohol use: 6.50, p<.01, partial η2 =.01; girls cigarette use: F (2, 1331) = 5.15, p<.01, partial η2 =.01; alcohol use: 8.77, p<.05, partial η2 =.01). Early maturing
