The relationship between subjective invulnerability and optimism bias in risk appraisal, and their comparative association with indices of risk activity, substance use and college adjustment problems was assessed in a sample of 350 (M [subscript age] = 20.17; 73% female; 93% White/European American) emerging adults. Subjective invulnerability was measured with the newly devised adolescent invulnerability scale (AIS). Optimism bias in decision-making was assessed with a standard comparative-conditional risk appraisal task. Results showed that the danger- and psychological invulnerability subscales of the AIS demonstrated strong internal consistency and evidence of predictive validity. Subjective invulnerability and optimism bias were also shown to be empirically distinct constructs with differential ability to predict risk and adjustment. Danger invulnerability and psychological invulnerability were more pervasively associated with risk behavior than was optimism bias; and psychological invulnerability counter-indicated depression, self-esteem and interpersonal problems. Results support recent claims regarding the "two faces" of adolescent invulnerability. Implications for future research are drawn.