Data reports from South Carolina's 92 independent school districts during 1980-81 were used to calculate prevalence rates of mental retardation and learning disabilities. These prevalence rates were 41.66/1,000 children enrolled for mental retardation and 33.21/1,000 children enrolled for learning disabilities. Additional analysis showed that community socioeconomic status and tax inputs explained 39% of the variation in prevalence rates. (Author/DB)