Recent studies have shown that typically developing children's emotion understanding is linked to the quality of their social adaptation with peer and adults. However, few studies have investigated this relation in adults with mental retardation. The present research investigated the role of social adaptation on emotion understanding within a sample of adults with mental retardation and within a sample of typically developing children of 6 to 10 years of age. Samples were matched regarding their social adaptation. Social adaptation was assessed with the ICAP (Bruininks, Hill, Weatherman & Woodcock, 1986). Emotional understanding was tested with the TEC (Pons & Harris, 2000). Preliminary analyses showed: (1) differences in emotional comprehension between adults with mental retardation and typically developing children; (2) some significant correlation between emotion understanding and social adaptation all samples together and within each samples. The results are discussed in terms of their theoretical and practical implications. Some of the results of this empirical research have been presented at the 18th Biennial Meeting of the International Society for the Study of Behavioral Development (ISSBD), Gant, Belgium (Hernandez Blasi, Escalera & Pons, 2004). This empirical research is still running. With Carlos Hernandez Blasi (University of Jaume I) and Cinta Escalera (Valencian Institute for Handicapped People).