Despite the global importance of mutuals in financial services, and the universal need to measure and improve organizational efficiency in all deposit-taking institutions, it is only relatively recently that the most advanced econometric and mathematical programming frontier techniques have been applied. This paper provides a synoptic survey of the comparatively few empirical analyses of frontier efficiency measurement in deposit-taking financial mutuals, comprising savings and loans, building societies and credit unions in Australia, the United Kingdom, and the United States. Both estimation and measurement techniques and the determinants of efficiency are examined. Particular focus is placed on how the results of these studies may help inform regulatory policy and managerial behaviour.