A teacher training program was implemented over a 2-year period in cooperation with the Tucson Unified School District, where over 28% of the students have been identified as having a primary language other than English. The goal of the training was to provide a forum wherein teachers and administrators would explore the application of ethnographic/sociolinguistic theories and methodologies as these can be applied to language proficiency assessment practices. The training was implemented in three phases. Phase I was a graduate level course for participating teachers which focused on models of language proficiency, and language proficiency in the bilingual classroom and community. Phase II consisted of the development of field techniques and a teacher observation instrument (TOS). Central to this instrument is a consideration of the social contexts used to describe students' language behavior. Phase III consisted of several stages: identification of issues for field testing of the TOS, more formal training for teachers in microethnographic/sociolinguistic field methods, and development of criteria for analyzing TOS field test results. Finally, the limitations and significance of the teacher training program are described in order to provide evaluative information regarding the ethnographic/sociolinguistic approach to language proficiency assessment. (AMH)