The National Assessment of Educational Progress in-school sampling design is a three-stage stratified design. Stratification variables include region, size of community and socioeconomic status. The three levels of sample selection are Primary Sampling Units (PSUs), schools and students. In general, two and sometimes three PSUs are selected from each stratum for variance estimation. The stratification variables are assumed fixed and not subject to change; therefore, the problem of finding the optimal design is reduced to finding the number of PSUs, schools and students per stratum that will minimize cost for a given variance. Following a brief overview of the sample drawn for Year 11, presented in Section 2, the cost model developed for the purpose of the present study is outlined in Section 3. Section 4 describes the statistics which were selected for analysis, and Section 5 derives the corresponding variance and covariance component models. Finally, Section 6 describes the optimization procedure used, and Section 7 provides a summary of the results. Primary type of information provided by report: Procedures (Sampling). (Author/BW)