This descriptive study examined urban elementary school teachers' perceptions of their science content knowledge, science teaching practices, and support for language development of English language learners. Also examined were teachers' perceptions of organizational supports and barriers associated with teaching science to nonmainstream students. The study involved 221 third- through fifth-grade teachers from 15 urban elementary schools in a large school district. The teachers completed a survey in the spring of 2005. The internal consistency reliability estimates, Cronbach alpha, for scales created from the survey items were within an acceptable range. The teachers reported that they were generally knowledgeable about science topics at their grade level and that they taught science to promote students' understanding and inquiry. In contrast, the teachers reported rarely discussing student diversity in their own teaching or with other teachers at their schools. The teachers identified specific organizational supports and barriers in teaching science with diverse student groups at both the school and classroom levels.