The response styles theory of depression (Nolen-Hoeksema, 1991) proposes three main strategies individuals employ in response to low mood: rumination, active coping (distraction and problem-solving) and risk taking. Although recent research has suggested this theory has utility in understanding the symptoms of bipolar disorder (BD), the role of these processes in conferring vulnerability to the condition is poorly understood. Twenty-three adolescent children of patients with BD and 25 offspring of well parents completed the Experience Sampling Method (ESM; Csikszentmihalyi and Larson, 1987) diary for six days. Longitudinal analyses were carried out to examine inter-relationships between mood, self-esteem and response styles. Increased negative as well as positive mood resulted in greater rumination in both groups. Low self-esteem triggered greater risk-taking at the subsequent time point in the at-risk group, while negative affect instigated increased active coping in the control group. In both groups, engagement in risk-taking improved mood at the subsequent time point, whilst rumination dampened self-esteem. Differential longitudinal associations between mood, self-esteem and response styles between at-risk and control children suggest early psychological vulnerability in the offspring of BD parents, with important indications for early intervention