In recent years, increasing numbers of grandparents in the U.S. are living with their grandchildren, and many grandparents are responsible for their care. These trends can be attributed to a number of factors, including increasing numbers of single-parent families, continued high rates of marriage dissolution, parents' incarceration, parental substance abuse, and difficult economic circumstances. In addition, situations that have long accounted for some care by grandparents are parents' death or serious disability, parental abuse or neglect, and family/cultural preference. This brief examines recent trends, national and for each state, associated with grandparents who live with grandchildren, based on data from the American Community Survey. (Contains 3 endnotes.)