While handwashing with soap (HWWS) has been identified as a major pathway to reducing the risk of diarrhoeal diseases, and respiratory infections, rates of HWWS remain low across the globe. The current study, a national survey of Ghanaian mothers, found that as few as 4% of mothers engaged in HWWS after defecation, and only 2% after cleaning a child's bottom. In a multivariate analysis, we explored the determinants of handwashing at these key junctures, with and without soap. After defecation, mother's education, knowledge of important times to handwash with soap, the age of her children, and a measure of the quality of child care were all associated with handwashing (in any form). However, only the latter two variables also predicted soap use amongst handwashers. After cleaning a child's bottom, education, knowledge of important times to handwash with soap, and child care quality were associated with handwashing (in any form), yet only one variable, a measure of disgust sensitivity, showed any possible relationship with soap use. While this study has several important limitations, failure to explain much of the observed variance, despite a large range of potential determinants explored, suggests that we need to continue complementing quantitative surveys with in-depth qualitative studies if we are to better understand the motivations for, and constraints to, HWWS in community settings.