A recent experimental study found that activation of negative body image cognitions produced urges to smoke in young women (E. N. Lopez, D. J. Drobes, J. K. Thompson, & T. H. Brandon, 2008). This study intended to replicate and extend these experimental findings by examining the role of negative affect as a mediator of the relationship between body dissatisfaction and smoking urges. Female college smokers (N = 133) were randomly assigned to a body image challenge (trying on a bathing suit) or a control condition (evaluating a purse). State levels of urge to smoke, mood, and body dissatisfaction were assessed both pre- and postmanipulation. Trying on a bathing suit increased body dissatisfaction and reported urges to smoke, particularly those urges related to reducing negative affect. Additionally, state negative affect mediated the relationship between the body image manipulation and smoking urge. This study provides additional support, through an experimental design, that situational challenges to body image influence smoking motivation and that this effect occurs, at least in part, through increases in negative affect. Theoretical and applied implications are discussed.