Age patterns and predictors of cannabis initiation among biracial and monoracial U.S. youth

<i>Background:</i> Understanding cannabis initiation is essential for effective prevention but remains understudied, especially for biracial youth who are disproportionately affected by substance use. <i>Objectives:</i> This study examined age patterns and predictors of cannabis initiation across eight monoracial and biracial groups and explored whether predictor effects varied by age, racialized group, and sex. <i>Methods:</i> Add Health data (<i>n</i> = 12,941, 50% male, baseline mean age = 15.5) were analyzed using discrete-time survival analyses to estimate cannabis initiation probabilities from ages 10–24 by age, racialized group, and other predictors. <i>Results:</i> Cannabis initiation probability followed a quadratic age pattern, increasing from age 10–16 and declining thereafter, with differences by racialized group (<i>p</i> &lt; .05). The highest probabilities of new initiations (at age 16) ranged from lowest to highest as follows: Asian (0.08), Black (0.10), Hispanic (White) (0.12), White (0.15), Biracial White-Indigenous (0.16), Indigenous (0.18), Biracial White-Black (0.19), and Biracial White-Asian (0.25). Age- and race-varying effects were found for peer substance use and parental control (joint Wald test, <i>p</i> &lt; .05). Specifically, peer substance use was positively associated with cannabis initiation during adolescence, peaking in mid-adolescence, with stronger effects for Biracial White-Black and Biracial White-Asian youth than their monoracial peers. The effects of parental control showed complex, group-specific patterns. Family support and religiosity slightly lowered cannabis initiation across racialized groups. <i>Conclusion:</i> These findings highlight distinct cannabis initiation patterns across racialized groups, along with variations in the effects of peer substance use and parental control by age and racialized group.