This study examines transitions in grandchild care and the characteristics of grandparents making these transitions, using longitudinal data from a nationally representative sample of 13,626 grandparents in the 1998-2008 Health and Retirement Study. More than 60% of grandparents provided grandchild care over the 10-year period; more than 70% of those did it for 2 years or more. Grandparents with fewer functional limitations and more economic resources were more likely to start or continue nonresidential care, whereas relatively disadvantaged grandparents were more likely to start and continue coresidential care. Grandparents who were African American, younger, married, living with fewer minor children of their own, or had more grandchildren were more likely to start care, particularly nonresidential care. African Americans and Hispanics were more likely than Whites to start and continue coresidential care. These findings demonstrate the heterogeneity of caregiving and point to the lack of resources among those who provide coresidential care.