This study examined the relative strength of the different factors contributing to diarrhoea among young children living in slum area of India. The paper also found evidence to suggest that the benefits of improved domestic hygiene are at least as large as those emanating from improvements in the quality of drinking water. With this caveat, this paper supports an accumulating body of research which points to the importance of soap for hand-washing as a prophylactic against diarrhoeal diseases. In turn, these findings point to a set of anti-diarrhoea policies which are complementary to the more traditional emphasis on improving the quality of drinking water.