The contribution of family, friend, and neighbor caregivers to the overall supply of child care and the care and education of our nation's youngest children is substantial. This brief explores, for policy and other audiences, some of the issues around measuring quality in family, friend, and neighbor care. The purpose is not to provide a comprehensive review of studies addressing quality in this setting, but rather to describe some of the challenges of this effort. It discusses reasons parents' choose this care and their associated definitions of quality, distinguishing characteristics of this care, and concerns with commonly used measures not designed for use in this setting. It also highlights some new advances in the field around definitions and measurement, the need to determine usefulness and relevance of new instruments, and some practical suggestions for testing cultural appropriateness and competency. (Contains 1 endnote.)