Professional culture is a key element for successful implementation and change in schools. The purpose of this paper is to triangulate collaboration networks and experiences of educators to describe the emergent professional cultures in three newly-opened pre-kindergarten schools. This paper uses an exploratory mixed-methods case study approach. The professional cultures of three pre-kindergarten schools were explored using descriptive social network analysis of 75 educators' collaboration within their schools and semi-structured interviews of 20 selected participants. Findings indicate distinct cultures at each of the three schools. Variations in network cohesion, in the alignment between formal and informal networks, and personnel stability combined into different types of professional culture. Interview statements and examples provide evidence and point to the importance of staff turnover in the development of professional culture among early childhood educators. The key limitation is that this study explores networks at the end of their second year of operation. Given that networks evolve as personnel and structures shift, the findings represent only a moment in time. This study supports the local nature of teaching and suggests that districts and leaders should consider the professional culture, and the specific role of the staff turnover, in that work. This study provides the rare opportunity to explore professional culture within brand-new school sites. It extends the existing literature by comparing three early childhood sites with different daily experiences of the same focused work.