In a German online study (n = 494) on fruit and vegetable intake, social-cognitive variables and stages were assessed at baseline and stage transitions 4 weeks later. Transitions between the preintention, intention and action stage were predicted by social-cognitive variables using binary and multinomial logistic regression analyses. Outcome expectancies predicted progression from the preintention stage, whereas social support predicted progression to the action stage. Low levels of planning were associated with relapse to the preintention and the intention stage. Self-efficacy emerged as a universal predictor of stage transitions.