The clinical utility of a model of normal emotional functioning (vs. psychopathology) and the moderating effects of neuroticism (N) and extraversion (E) on mood were examined during a 6-week weight-loss trial. Participants were 40 obese women who completed measures of negative affect (NA) and positive affect (PA) weekly during the diet and measures of anxiety and depression (Beck Depression Inventory [BDI]) at pre-, mid-, and postdiet. Results indicated that (a) average NA and PA were each uniquely related to postdiet BDI scores, (b) N was significantly related to NA during the diet and postdiet BDI scores, and (c) N and E interacted to predict PA during the diet. The results suggest that assessment of personality and normal mood variation may be useful additions to weight-loss intervention and research.