According to the U.S. Census Bureau, nearly one quarter of children under 5 years old are in the care of their grandparents for some period of time every week while mothers work (2013). The Grandparents Who Care project explores the benefits and challenges of such kinship care and provides guidance concerning grandparents' needs and how best to address them. In preparation, we interviewed experts in the field, reviewed research on the grandparent-grandchild relationship, and examined studies on grandparents who have assumed a caregiving role. This document summarizes our key findings. (author abstract)