If language is the result of specialized structures in the brain and if these language-specific structures are genetically encoded, one would expect to find evidence of the heritability of language. In this article I review the results of family aggregation, pedigree, sex ratio, commingling, and segregation studies of spoken language disorders. The results of these studies provide evidence that, although spoken language disorders are genetically and behaviorally heterogeneous, genetic factors may play a substantial role in many cases of developmental spoken language disorders.