The Children's Bureau of the Administration on Children, Youth and Families, U.S. Department of Health and Human Services, has undertaken the National Survey of Child and Adolescent Well-Being (NSCAW) to learn about the experiences of children and families who come in contact with the child welfare system. NSCAW is gathering information associated with over 6,200 children from public child welfare agencies in a stratified random sample of 92 localities across the United States. The first national longitudinal study of its kind, NSCAW is examining the characteristics, needs, experiences, and outcomes for these children and families. The study will provide information about crucial program, policy, and practice issues of concern to the Federal government, state and local governments, and child welfare agencies. This report provides information about the characteristics of children and families who came into contact with the child welfare system through an investigation by child protective services. It provides a snapshot of the functioning and the potential service needs of children and families soon after a child protective services investigation has taken place. The study provides unique information about the effectiveness of efforts to intervene in the poor developmental trajectories of children involved with CWS. This report is organized into 12 chapters. Following an introduction, Chapter 2 provides a general overview of the NSCAW survey design and data sources, with a particular emphasis on the CPS component. The chapter also addresses response rates and potential sample bias. Chapters 3 through 5 examine the characteristics of the children in the CPS component of NSCAW. These chapters focus on the characteristics of the children, the environment in which these children live, and their developmental and functioning status. Chapter 6 addresses characteristics of the current caregivers. Chapter 7 describes the relationships between these children and their current caregiver. Chapter 8 examines children's service needs and receipt, and Chapter 9 the service needs and experiences of in-home current caregivers. Chapter 10 summarizes findings from a developmental perspective. Finally, Chapter 11 provides a summary of the findings and offers possible lessons for policy and practice that may be drawn from baseline data and analysis. Two appendixes are included: (1) Selected Analyses for Key States; and(2) Reliability of NSCAW Measures. (Contains 247 tables and 35 footnotes.)