Strategies for creating and maintaining reciprocal partnerships between teachers and parents are considered essential elements of developmentally appropriate practice in early childhood education (ECE). Particularly for children who are high-risk for behavioral, developmental, or mental health problems, effective partnerships between family and preschool are essential for promoting optimal classroom participation and learning outcomes. The current study is an uncontrolled (pre-post) feasibility trial of Family-School Partnership Intervention (FPSI). FSPI was developed using stakeholder input, is delivered by existing preschool staff, and aims to promote development and reduce barriers to learning among children with pre-clinical social-communication delays. FSPI integrates evidence-based practices (EBPs) from education (7 EBPs; National Association for the Education of Young Children) with clinical interventions for toddlers with autism spectrum disorder (ASD) (12 EBPs at the educator-parent level and 8 EBPs at the parent-child level; Naturalistic Developmental Behavioral Interventions). Data will be collected across 10 ECE programs. At each participating ECE program, research procedures will be completed during a single school year. Selected ECE programs will include public school, Head Start, and private preschool programs. Participants include 20 non-teaching support staff (1-2 per program; e.g., director, principal, education-coordinator), 30 lead teachers (2-4 per program), and 60 children with social-communication deficits (two per teacher). Data collection will focus on feasibility data (enrollment, attendance, attrition, data completion), observational measures of implementation fidelity (at the educator-parent and parent-child level), and mixed methods to evaluate educator and parent acceptability and satisfaction and identify implementation drivers/barriers. This research will prepare a large, multi-site hybrid trial to evaluate the effectiveness of FSPI for promoting social-communication skills and kindergarten readiness, in addition to factors that mediate the relation between FSPI delivery and fidelity (implementation drivers/barriers).