Previous research demonstrates that integration of science and literacy instruction in primary grades has positive outcomes for students' science and literacy development. However, variations in how science and literacy are enacted suggest integration may not be sufficient to meet the literacy and science needs of all students in an equitable manner. The purpose of this study was to examine two first-grade teachers' science integration during literacy instruction in one high- and one low-income school context within one urban district. Analysis of field notes, transcripts of lessons, and interviews revealed that expectations to integrate science during time set aside for literacy instruction without consideration of contextual factors perpetuated and concealed ongoing inequities in science education for students from the lowest income school. Further, this study adds to evidence from prior studies demonstrating that reading of science-related texts alone, as a substitute for instruction in science as a discipline, does not provide students with the resources needed to learn to think, talk, and act as scientists. Findings from this study require researchers and policy-makers to address the context-specific factors that shape instructional contexts in ways that limit or expand the potential of integrated science--literacy instruction in urban schools.