Objective: Although laboratory experiments suggest that negative affect inductions potentiate the relation between dieting and disinhibited eating, little research has tested whether this finding generalizes to binge eating in the natural environment. Thus, we assessed whether negative affect moderated the relation between dieting and binge eating in a passive-observational study. Method: This aim was addressed with longitudinal data from a community Sample of adolescents (N = 631). Results: For females, dieting and negative affect predicted binge eating in cross-sectional and prospective analyses, but negative affect potentiated the relation between dieting and binge eating only in the cross-sectional analyses. Similar, but attenuated results were found for males. Discussion: Findings converge with those from laboratory studies in suggesting that negative affect moderates the relation between dieting and binge eating, but also imply that dieting and negative affect constitute independent risk factors for binge eating. The lack of prospective effects may suggest that the interactive relations have a short time lag or are difficult to detect prospectively. (C) 2000 by John Wiley & Sons, Inc.