This article presents a case for distinguishing between mental retardation as a general deficit of thinking and mental retardation that might result from the global effects of a specific: deficit in a cognitive module. Using Anderson's (1992a) theory of the minimal. cognitive architecture of intelligence and developmental, I show how this distinction can explain the pattern of intellectual strengths and weaknesses in Savant syndrome, Williams syndrome, Down syndrome, and autism. In addition, I discuss the developmental versus difference view and the distinction between organic and cultural familial mental retardation in the light of this theory. I conclude that not only is there no inherent incompatibility between the constructs of general intelligence and modularity of mind but that both are essential to understanding the different patterns of abilities and developmental profiles found in individuals with low IQ.