Two studies examined the main assumption of the Prototype/Willingness Model for eating behavior. Accordingly, health-behavior in adolescents results from intentional and social-reactive processes, namely behavioral intentions and behavioral willingness. The hypothesis was that willingness explains eating behavior over and above intentions with respect to eating behavior in general and in the peer context. This was tested in a cross-sectional (N = 286) and a longitudinal (N = 335) study. Intentions and willingness were assessed for healthy and unhealthy eating, eating behavior using an eating pattern index, and observed food consumption in the peer context. Willingness explained variance in eating behavior over and above intentions. Intentional as well as social-reactive processes contribute to adolescents’ eating behavior. Implications for practice are discussed.