Each of the three chapters in this dissertation is a separate consideration of one aspect of language acquisition by Tenejapa Tzeltal children. Chapter I places the specification of input sources and contexts in a matrix of the ethnographic description of the childhood portion of the life cycle in Tenejapa. Beliefs and practices that have a direct or indirect bearing on language acquisition are emphasized. Chapter II deals with some facets of Tzeltal plant taxonomy and nomenclature, examining interconnections between the two systems, and classifies children's responses when identifying plants in an attempt to isolate trends of lexical development. Chapter III deals with problems and results of analyzing data gathered, suggests a priority in focus of performance over competence, and proposes the presence in young children of an aural analogue to the phenomenon of eidetic imagery which bolsters the hypothesis that there is a critical age for first language learning. Appendices present (1) the orthography of Tzeltal words used and a brief outline of some of the more interesting features, (2) some notes on the field situation, (3) a compilation of the plant identification data used in the analysis of Chapter II, and (4) a compilation of the elicited imitation data that was used in the analysis of Chapter III. (DO)