Co-teaching has increasingly been utilized as an alternative model for the student teaching experience in pre-service education. Recent literature highlights potential for co-teachers to develop by engaging in cycles of inquiry in learning communities. The purpose of this study was to explore the experience of a science student teacher who engaged in cycles of inquiry around supporting English language learners (ELLs) in a co-teaching student teaching placement. This qualitative case study involved a science mentor teacher and a science student teacher engaged in a yearlong co-teaching placement. Data sources included surveys, interviews, and written and oral lesson plans and reflections. Four affordances were identified as assisting the student teacher in her efforts to support ELL students during the co-teaching experience: identification of ELL needs, purposing science labs, focusing on ELLs, and competence validation. Three constraints appeared to limit the student-teacher’s ability to support ELL students during her co-teaching student-teaching experience: perceived multiple purposes for science labs, time constraints, and power dynamics in the co-teaching relationship. This study provides insights into potential benefits and challenges associated with the use of co-teaching with professional learning communities and cycles of inquiry as a model of teacher preparation.