The National Longitudinal Transition Study (NLTS) of Special Education Students provides ongoing information regarding the transition of youth with disabilities from secondary school to early adulthood. The sample for the study, which began with a 1987 survey (Wave 1), involved more than 8,000 youth from the national population of secondary special education students. Wave 1 had four major components: the parent interview, abstraction of data from school records, the survey of secondary special education programs, and the nonresponse study. This report describes the study's sample and study design features, including the definition of the universe; the methods used to build the sampling frame and select the sample; the response rates and efforts to increase them; procedures for weighting the data; and limitations of the sample and design. Conclusions address: (1) how well the sample is able to estimate school status; (2) comparison of the NLTS estimates of the number of students in each disability condition with U.S. Department of Education counts; and (3) limitations of the sample. The report examines the relatively high nonresponse rates but concludes that the NLTS meets high standards with respect to its procedures and will prove to be useful and valid for policy decisions and for social and scientific analyses. Sixteen tables detail the report's findings. (DB)