This study examined language maintenance through a sociology study of K'iche', a Mayan language of Guatemala, where a stable diglossic situation is eroding in the face of an increasing tide of bilingualism. Seven K'iche'-speaking communities were examined, including an analysis of socioeconomic, demographic, and political data. Quantified observations were made of the speech transactions of 11,229 speakers. Qualitative data were examined in the framework of Ethnolinguistic Identity Theory. Quantitative data were subjected to statistical analysis using categorical models, maximum likelihood analysis, and chi-square to determine the effect of race, sex, age, and domain on language use. A Language Maintenance Index was calculated for each age group and domain of use. A Global Language Maintenance Index permitted comparison of intercommunity language maintenance levels. The communities were found to be at different levels of language maintenance in spite of an intact diglossic relationship between Spanish and K'iche'. The communities have different combinations of ethnolinguistic identity factors and the differences in language maintenance levels can be related to differences in demographic, institutional support, status, and subjective vitality factors. (Contains 19 references.) (Author/NAV)