The Early Childhood Longitudinal Study (ECLS) is a new study that will focus on children's early school experiences beginning in kindergarten. Approximately 23,000 children will be selected as they enter kindergarten and followed through fifth grade. Base-year data will be collected in the fall of 1998, but there will a field test in the 1996-97 school year. This paper, prepared in support of the development of the ECLS, reviews nine studies, each of which may provide some design features that would be useful in the ECLS. The studies reviewed are the: (1) Beginning School Study; (2) Children of the National Longitudinal Study of Youth; (3) Greensboro Early Schooling Study; (4) Prospects: The Congressionally Mandated Study of Educational Growth and Opportunity; (5) District of Columbia Early Learning and Early Identification Study; (6) National Education Longitudinal Study of 1988 (NELS:88); (7) Canadian National Longitudinal Survey of Children; (8) National Survey of Children; and (9) National Child Development Study. In reviewing the design and results of these studies, several cross-cutting issues were recognized, including the cognitive assessments, the social and emotional measurements, and the measures of environment. Issues concerning overall study design are also explored, and individual summaries are provided for each of the studies. Study design and sampling and administration procedures will be largely based on the experience of the NELS:88. Each of the study summaries contains references. (Contains six tables.) (SLD)