This dissertation examines nonparticipation of 12th graders in the year 2000 National Assessment of Educational Progress (NAEP), using a model of nonresponse developed by Groves and Couper (1998). NAEP is a continuing assessment of American student knowledge in various subject areas including mathematics and science, and the possibility that its results could be contaminated by a low response rate was taken as very serious. The dissertation evaluates the statistical impact of nonparticipation bias on estimates of educational performance in NAEP, by applying response propensity models to the NAEP mathematics and science survey data and the corresponding school administrative data from over 20,000 seniors in the 2000 High School Transcript Study (HSTS). When NAEP and HSTS are merged, one has measures of individual- and school-level characteristics for nonparticipants as well as participants in NAEP. Results indicate that nonresponse was not a serious contaminant, and applying response propensity based weights led to only about a 1-point difference out on average of 500 points in mathematics and of 300 points in science. The results support other recent research (e.g., Curtin, Press and Singer, 2000; Groves, 2006) showing minimal effects on nonresponse bias of lowered response rates.