Detection, Assessment and Referral - Gatekeeper Protocol (DAR-GP) is an evidence-informed intervention developed by the National Suicide Prevention Program of Chile, which is part of a multi-tiered school-based suicide prevention model. DAR-GP outlines gatekeeper steps to assist and support at-risk students, involving not only training but also the procedures to implement the gatekeeper's role at school. Despite its nationwide dissemination, there are no implementation guidelines, and public schools have low adoption rates. To address this gap, an exploratory sequential mixed methods design is conducted to co-design and explore the feasibility, acceptability, and preliminary effects of an implementation facilitation strategy to adopt DAR-GP in Chilean public schools. The first phase involved a co-design process in which stakeholders with experience in mental health interventions in public schools informed the design of an IF model. The results comprise a blended strategy, including external and internal facilitation, combining two types of expertise: experience in implementation science and suicide prevention from external facilitation, and the lived experience in organizational culture and school implementation processes of internal facilitators from schools. Three IF phases are defined according to the implementation stages: preparation for change, aimed at supporting the awareness and engaging stakeholders; capacity building, which aims to strengthen the school's capacities for an adequate implementation plan and safely put the intervention into practice; and technical assistance, where IF accompanies the schools to monitor and evaluate the implementation for the sustainability of the intervention. The collaboration between external and internal IF operates in a gradient from higher to lower intensity through the phases, where the first phases contemplate a more active role of the external facilitator to progressively give way to a greater role for internal facilitation and the protagonism of the school. Finally, the presentation will analyze the methodological challenges and benefits of evaluating the implementation and intervention outcomes through a pilot hybrid evaluation.