Studies of desegregation effects on student achievement show no clear trends, although most of the studies report positive outcomes. The variance reported in desegregation studies has been attributed to: 1) type of desegregation plan; 2) duration of desegregation; 3) characteristics of the schools and communities involved; and 4) methodology used in desegregation research. In the Clark County, Nevada School District, changes in student achievement were observed between 1972 and 1981, a period during which the Sixth Grade Plan of Integration was in effect in the district. In September, 1972, the Plan of Integration established sixth qrade centers in what had been predominantly black neighborhood elementary zones. Sixth graders from throughout the metropolitan area were bused to the centers, while first to fifth grade black students from the zones in which the centers were located were transported to other schools in the metropolitan area. Comparisons of 1972 and 1981 student achievement measures indicated that since implementation of the Plan, academic performance among blacks, non-blacks, and whites improved, with the gains being particularly pronounced among blacks. Achievement differences between blacks and other student subgroups persisted, although the gains recorded by blacks greatly reduced the disparity. If trends continue, the disparities may eventually disappear. (Author/MJL)