Sometimes it seems intuitively plausible to hold loosely structured sets of individuals morally responsible for failing to act collectively. Virginia Held, Larry May, and Torbjörn Tännsjö have all drawn this conclusion from thought experiments concerning small groups, although they apply the conclusion to large-scale omissions as well. On the other hand it is commonly assumed that (collective) agency is a necessary condition for (collective) responsibility. If that is true, then how can we hold sets of people responsible for not having acted collectively? This paper argues that that loosely structured inactive groups sometimes meet this requirement if we employ a weak (but nonetheless nonreductionist) notion of collective agency. This notio...