This study examined the determinants of attributions for success or failure in stopping smoking in a self-help treatment program with and without a drug component. Subjects (N=137) were randomly assigned to one of three experimental conditions: (1) nicotine gum and a self-help manual with an intrinsic motivational orientation; (2) self-help manual with an intrinsic motivational orientation only; and (3) nicotine gum and a self-help manual with an extrinsic motivational orientation. At follow-up interviews, patients rated the extent to which their continued non-smoking or their trouble in quitting completely were influenced by their own efforts, their abilities, the challenge of quitting, an unexpected event, and their doctor. The results revealed a significant main effect for smoking status on internal attributions. Ex-smokers made higher internal attributions for success than did smokers for failure to quit. The interaction of the motivational orientation with status was significant in that smokers in the intrinsic conditions made higher internal attributions for their failure than did smokers in the extrinsic group. Patients' success or failure in quitting influenced their attributions independently of treatment condition. Quitters made more internal and less external attributions for their smoking status than did smokers. These attributions may also predict continued abstinence. (NB)