Reported here are the results of analyses to describe the patterns of identification and academic and developmental outcomes for children with disabilities, conducted as part of the 2004 National Assessment of the implementation of the Individuals with Disabilities Education Act (IDEA). This report provides background context for National Assessment studies on program implementation and effectiveness. It provides a national description of the outcomes of children identified for services under IDEA and, as appropriate, in comparison with the outcomes of samples including their nondisabled peers. The results are presented by the age groups that correspond with a federal and local emphasis on children younger than school age and in elementary, middle and high schools, ages 0–3, 3–5, 6–9, 10–13, and 14–17. Further, the findings are reported across a 10-year time frame as well as for a single time point, describing a comprehensive picture of identification patterns and outcomes for each age group. Finally, extant data sources were used for analysis rather than costly new data collection. This report objectively presents descriptive findings from these analyses and provides relevant contextual information, such as the legislative background on IDEA. This study was not designed to assess how outcomes presented in this report are affected by identification or declassification practices, nor is it designed to measure impacts of IDEA services on child outcomes.