ABSTRACT: BACKGROUND:Across the United States, sexually transmitted infections and unintended pregnancy rates are alarmingly high among youth. Schools, due to their proximity and access to youth, can increase student access to sexual health services (SHS) by creating referral systems (RS) to link students to school- and community-based SHS. From 2013 to 2018, the Centers for Disease Control and Prevention's Division of Adolescent and School Health funded 17 Local Education Agencies (LEA) to partner with priority schools and stakeholders to develop and implement RS to increase student access to SHS. Cicatelli Associates Inc. (CAI) was funded to provide capacity-building to LEA. In 2016-2017, CAI conducted case studies at two LEA, both large and urban sites, but representing different geographical and political contexts, to elucidate factors that influence RS implementation. METHODS:Nineteen LEA and community-based healthcare (CBH) staff were interviewed in the Southeastern (n?=?9) and Western U.S. (n?=?10). Key constructs (e.g., leadership engagement, resources, state and district policies) across the five domains of the Consolidated Framework for Implementation Research (CFIR) framework guided the methodology and analysis. Qualitative data was analyzed using the Framework Method and contextual factors and themes that led to RS implementation were identified. RESULTS:Interviewees strongly believed that school-based RS can decrease STI, HIV and unintended pregnancy and increase students' educational attainment. We identified the following contextual key factors that facilitate successful implementation and integration of an RS: enforcing state and district policies, strong LEA and CBH collaboration, positive school culture towards adolescent health, knowledgeable and supportive staff, leveraging of existing resources and staffing structures, and influential district and school building-level leadership and champions. Notably, this case study challenged our initial assumptions that RS are easily implemented in states with comprehensive SHS policies. Rather, our conversations revealed how districts and local-level policies can have significant impact and influence to impede or promote those policies. CONCLUSIONS:Through the use of the CFIR framework, the interviews identified important contextual factors and themes associated with LEAs' implementation barriers and facilitators. The study's results present key recommendations that other LEA can consider to optimize integration of RS-related evidence-based practices, systems, and policies in their districts.