Objective: We assess the association between conscientiousness and adherence to the oral contraceptive pill (OCP), and examine if such a relationship is independent of a measure of prospective memory and a range of social cognitive variables.Method: Data were collected from 150 OCP users at baseline, and 99 provided follow-up data four weeks later. Conscientiousness, a range of social cognitive predictors and prospective memory were assessed at baseline. OCP adherence was measured at baseline, and again at Time 2. Data were analysed using correlation and multiple linear regression.Results: Higher conscientiousness was associated with higher overall OCP adherence in both cross-sectional (r=-0.28, p<0.01) and prospective analysis (r=-0.34, p<0.01). Conscientiousness predicted OCP adherence at Time 2, adjusting for OCP adherence at Time 1 (R-2 change=0.02, p=0.04). The association was reduced to non-significance when social cognitive predictors and prospective memory were included in the multivariable model. Prospective memory was an independent predictor of OCP adherence at Time 2.Discussion: This is the first study to identify an association between conscientiousness and OCP adherence. The association is not independent from social cognitive predictors and prospective memory. Facet-level analysis of conscientiousness and formal mediation analyses are recommended in future replications.