Designed by the Ilinois Bilingual Evaluation Center as a pilot project, the purpose of this study was to explore the process or nature of events in a bilingual classroom and to investigate the feasibility of using observational techniques to examine this process in an evaluation context. The subjects for the study were three children of Spanish speaking background enrolled in a grade one half-day bilingual program. Each child was videotaped for a full school day, three times throughout the year. The data reported in this paper are taken from the first set of videotapes. Two preliminary analyses are presented. The first is an ethnographic analysis of the language interaction patterns of the target children and their bilingual teacher. The amount of time each language (Spanish and English) is spoken and a functional analysis of language use is discussed. The second analysis is an ecological comparison of the bilingual and regular classrooms as behavior settings. Social and psychological aspects of language use as they vary across settings are discussed. (Author/BW)