Ed-LinQ is a mental health policy initiative to enhance the early detection and treatment of children with mental illness by improving the liaison between schools and health services in Queensland, Australia. We measured its impact from policy to practice to inform further program developments and public strategies. We followed a mixed quantitative/qualitative approach. The Adoption Impact Ladder (AIL) was used to analyse the adoption of this initiative by end-users (decision makers both in the health and education sectors) and the penetration of the initiative in the school sector. Survey respondents included representatives of schools (n = 186) and mental health providers (n = 78). In total, 63% of the school representative respondents were at least aware of the existence of the Ed-LinQ initiative, 74% were satisfied with the initiative and 28% of the respondent schools adopted the initiative to a significant extent. Adoption was higher in urban districts and in the health sector. The overall level of penetration in the school sector of Queensland was low (3%). The qualitative analysis indicated an improvement in the referral and communication processes between schools and the health sectors and the importance of funding in the implementation of the initiative. Mapping of existing programs is needed to assess the implementation of a new one as well as the design of different implementation strategies for urban and rural areas. Assessing the adoption of health policy strategies and their penetration in a target audience is critical to understand their proportional impacts across a defined ecosystem and constitutes a necessary preliminary step for the evaluation of their quality and efficiency.