A majority of Americans have a casual sexual experience before transitioning to adulthood. Little research has yet to examine how identity influences causal sexual behavior. The current study fills this gap in the literature by examining if subjective adult identity predicts casual sexual behavior net of life course transitions in a national sample of Americans. To answer this research question, the Longitudinal Study of Adolescent to Adult Health is utilized. Structural equation modeling results show the older and more adult-like individuals feel the less likely they are to report a recent casual sexual partner. Once life course factors are included in the model, subjective identity is no longer associated with casual sex. Practitioners who work with adult populations need to consider how life course transitions influence casual sexual behavior.