This study explored the relative effects of self-efficacy on oral contraceptive use among a sample of 352 Iranian married women aged 18–49 years. In structured interviews 5 variables based on the Steps to Behaviour Change model (knowledge, approval, intention, practice and advocacy) were assessed and correlated with measures of family planning self-efficacy and general self-efficacy. The results indicated that the 2 independent measures, when taken together, were more effective in predicting behavioural intentions for effective use of oral contraceptives, with family planning self-efficacy making the strongest contribution. It is suggested that self-efficacy intervention techniques will benefit oral contraceptive users in preventing unintended pregnancies.