This study explores the understandings that young Mexican-American students develop about the status of languages and language use in their bilingual school. The term linguistic ecology is used in this paper to describe the communicative behaviours of a group, as well as the physical and social contexts in which those exchanges occur. The data strongly suggest that children in bilingual classrooms discern the critical lack of support to maintain their first language. This case study documents and interprets the social and educational processes through which bilingual children in one US school come to appreciate the prestige and power of English versus Spanish. It is through their recognition of the greater social status afforded English — even in bilingual programs — that motivates them to transition away from their mother tongue.