Carolina Abecedarian Project Through Age 21, by Frances Campbell, Craig Ramey, and others

Chicago Child-Parent Centers Longitudinal Study Through Age 20, by Arthur Reynolds and others

Washington, DC, Preschool Model Study, by Rebecca Marcon

National Institute for Early Education Research (NIEER)

The Georgia Early Childhood Study: 2001–2004. Final Report, by Gary T. Henry

The United Kingdom's Effective Provision of Pre-School Education (EPPE) Project, by Kathy Sylva, Edward Melhuish, Iram-Siraj Blatchford, Pam Simmons, and Brenda Taggart