Participation in high quality early intervention programs is critical for eligible young children who experience atypical development for their future academic success. High quality programs promote access to services, incorporate instructional strategies that encourage children's participation, and advocate public policy that supports professional development and collaboration among families, early childhood educators, and early intervention providers. Although program implementation according to evidence-based practice is recognized as the key, little research currently exists documenting the implementation of evidence-based practices in early intervention programs. The primary goal of this mixed-methods study was to determine if families, early childhood educators, and early intervention service providers were knowledgeable about evidence-based practices for early intervention and if these practices were currently being implemented consistently throughout the Commonwealth of Pennsylvania. Families (n = 11), early childhood educators (n = 149), and early intervention providers (n = 66) completed online surveys, and 12 participants participated in semi-structured interviews to report their experiences. Early intervention providers reported a significantly higher perception than early childhood educators that early intervention services were implemented according to evidence-based practice. Early childhood educators were knowledgeable about evidence-based practices in early intervention, but they did not feel they were implemented in their programs. Study findings are discussed in the context of providing early childhood educators with recommendations for improving the quality of early intervention implementation for children with atypical development in their community preschools including access, participation, and policy support.