It is generally recognized that a positive relationship exists between language ability and mental ability as measured by a standard intelligence test. The relationship has been suspect, however, since the understanding and use of words play so large a part in many of the intelligence tests. The question has been raised of whether a child earns a high score on a verbal intelligence test because he/she has a good command of language, or whether he/she has a good command of language because of verbal intelligence. This review of historical research addresses the relationship between language and intelligence. The review focuses on studies of cognitive development which relate, in some respect, to the various definitions of intelligence. (Contains a 53-item bibliography of research published between 1926 and 1969.) (NKA)