Excerpt from introduction: The majority of all children in American families now regularly spend time under the care of someone other than their parents. The type of arrangement used, however, can vary depending on family income, household composition, and geographic location. Over time, the proportion of children in child care has grown and the types of arrangements have shifted. This occasional paper presents new findings from the 1999 National Survey of America's Families about the primary child care arrangements used by children under the age of 13 while the adults most responsible for their care (usually their mothers) are employed. It updates earlier reports that used 1997 data. Because care needs change dramatically once children enter school, the paper describes arrangements separately for preschool children (those under age 5), for 5-year-olds (who are transitioning into school settings), and for school-age children (those 6 through 12 years old). It compares the arrangements made by low-income parents with those made by higher-income parents and compares the arrangements made by single-parent and two-parent families. It also examines differences across selected states in 1999 and changes between 1997 and 1999 for the nation as a whole.