The purpose of this ethnographic case study was to study the language development of 4-year-old emergent bilinguals in a bilingual (Spanish/English) Head Start classroom with flexible language practices. Data were collected throughout the 10-month school year by visiting the classroom 2-3 times per week. Data include: field notes (observations and detailed notes of children language practices); transcriptions of interviews with teachers, families and administrators; and artifacts of children's work. The data were analyzed by examining shifts and patterns in the children's language practices over the year and the ways in which they negotiated language with others. Interviews with teachers, families and administrators provide insight into the language ideologies of the classroom, school and community. This paper highlights the language practices of two children to demonstrate the ways in which hybrid language practices, fostered by the teachers, created a classroom environment that allowed children to draw from their full linguistic repertoire to develop and engage with the curriculum. (author abstract)