A number of studies on the acquisition of communicative competence (the ability to communicate effectively in natural social settings) in varying cultural and social settings are described. Languages covered are English, including urban Afro-American dialects; Samoan; Tzeltal, an Indian language of Southern Mexico; Luo of Kenya; and the Spanish of California Chicano bilinguals. Substantive areas of concentration are acquisition of (1) syntax, (2) semantics, (3) social rules affecting choice of linguistic variants, (4) code switching in bilingual speech, and (5) relation of speech to grammar. The emphasis is on empirical investigations to test current speculations on psychological mechanisms for learning language and other human communicative abilities. (Author/FWB)