Bibliography: leaves 145-149. / In this dissertation we examine variation, in both speech and writing, in the South Sotho spoken in Lesotho. We indicate that the South Sotho used by a majority of speakers today shows a shift from both earlier and prescribed varieties. Open-ended questionnaires and informal conversations were used to study aspects of phonology, morphology, syntax, semantics and the lexicon of South Sotho. Samples were collected from speakers with ages ranging from twelve to over eighty. The dissertation shows that the age, social status, sex and locality of speakers are contributing factors in their language repertoire. We argue that South Sotho lacks the homogeneity that is claimed by language purists in Lesotho, and therefore has non-standard varieties, namely, dialects and sociolects. Although the structure of standard South Sotho sentences is relatively stable, the phonology, lexicon and semantics are indicative of major endogenous and exogenous changes. On the other hand, Sotho morphology shows endogenous changes only. The influence of English on South Sotho is increasing at the expense of Afrikaans influence.