The partial or total non-use of toilets, with some or all in a household defecating in the open, is a growing concern. Although all households may have a toilet, communities cannot remain open defecation free unless they are always used by everyone. This is not just an issue of maintenance and accessibility but also of social norms, mind-sets, and cultural preferences. The problem is widespread but most evident in India. This issue of Frontiers of CLTS asks how serious the problem is, why it occurs, what can be done about it, and what more needs to be known.