This study investigated mainstream preservice teachers' views on working with ELLs and factors affecting their views. Grounded in sociocultural theory, we develop the following three research questions: What are content teachers' understanding of working with ELLs and ESL teachers? In what ways, do content teachers plan to work with ELLs and ESL teachers? And what are the factors influencing their perceptions of ELLs? We employed the ground theory methodology to examine fifteen preservice teachers' perceptions of ELLs and their understanding of ELLs' needs. The findings showed their views on coursework modifications for ELLs, ambivalent attitudes toward supporting ELLs and working with ESL teachers, and misconceptions regarding second language acquisition. Based on the findings, the recommendations for teacher preparation were provided.