Ten studies investigating the relationship between mood change and weight loss in behavioral weight loss programs were reviewed. Significant positive changes in mood were observed in 6 of the 10 studies. There was no evidence to indicate that untoward reactions to dieting were frequent, that patients with juvenile-onset obesity experienced more negative mood changes than those with adult-onset obesity, or that dropping out of treatment was a response to increasing depression. The positive changes in mood were related to active participation in a treatment program, and occurred in behavioral and nonbehavioral treatment programs. Differences between the studies reviewed and the earlier research on mood and weight loss are discussed and suggestions made for subsequent studies of mood changes during weight reduction.