This study is an examination of early childhood preservice teachers' kindergarten internship experiences to identify the supportive and challenging conditions for their learning and explore in what ways those conditions are productive or unproductive for them, based on ecological perspective as a theoretical framework. Qualitative data were collected from weekly seminar notes and field notes by the researchers, a focus group with the preservice teachers, and course evaluation feedback. Through a constant comparative analysis approach, the findings indicate that both supportive and challenging learning conditions were created by collaborating teachers, preservice teachers, and the university supervisors. The findings illuminate the complex responsibilities of early childhood teacher educators to develop horizontal expertise for both themselves and preservice teachers so they can negotiate the best practices from research and the reality of school contexts.