Adolescent substance use (SU) is associated with risky sex behavior and sexually transmitted infections and is a risk factor for subsequent risky sex decisions. Based on a sample of 1,580 youth in residential SU treatment, this study investigated how a static factor (race) and two dynamic personal factors (risk-taking, assertiveness) contributed to adolescents’ perceived ability to avoid high-risk SU and sex behavior (avoidance self-efficacy). Results showed that race correlated with risk-taking and assertiveness, with White youth reporting higher ratings of assertiveness and risk-taking. Self-reported assertiveness and risk-taking also predicted SU and risky sex avoidance. This study underscores the importance of race and personal factors in relation to adolescents’ confidence in avoiding high-risk situations.