The introduction to this Special Topic Collection has two parts. To provide background and context for the articles in the collection, Part 1 tells the story of the Early Childhood Longitudinal Study program at the National Center for Education Statistics. It offers an abridged history of this program and describes the designs of the two national…

To date, no studies have documented how much early childhood experiences have changed over time. In the current study, researchers use two large, nationally representative datasets of kindergarten entrants to document the following: (1) How have children's early childhood experiences changed between 1998 and 2010?; (2) To what extent have…