Whereas a wealth of research has examined cognitive abilities of groups of individuals with mild mental retardation (MMR), less research has investigated potential differences in cognitive performance among individuals with mental retardation (Baumeister, 1997). The present study was an exploratory analysis of variability in performance of children with MMR on a wide range of cognitive tasks. Four-, 5, and 6-year-old children were presented with 10 cognitive tasks designed to tap different underlying processes. Children's performance on each of these tasks was only moderately correlated with IQ scores. Cluster analysis revealed four clusters of young children with MMR that were differentiated by their patterns of cognitive performance across the 10 tasks. Patterns of cognitive performance are described for each cluster and implications of this research are discussed. (Contains 4 tables and 1 figure.)