Adolescence is a formative phase of life which shapes the health and well-being of an individual for adulthood. In South Africa, adolescents are experiencing large and growing burdens of disease with high rates of communicable diseases (like HIV and TB), pregnancy, obesity, mental illness and trauma. Government policies to support adolescent healthcare have been widely implemented, however, challenges remain in how such policies are operationalised to strengthen adolescent healthcare: primary care clinics report low attendance of adolescents and school health reviews show low service provision. The Knowledge Translation Unit in Cape Town has developed the PACK Adolescent guide and training programme to support primary care clinicians (nurses and doctors) with tools to meet the needs of adolescents. The aim of this study is to understand the status of adolescent healthcare in primary care clinics and schools in order to refine and adapt PACK Adolescent to meet the needs of adolescents and the challenges faced by clinicians in providing care to this underserved grouped. Once refined, we shall pilot and evaluate PACK Adolescent in schools and clinics to see what more we need to do to optimise PACK Adolescent and what we need to alter about the delivery of adolescent healthcare to enable its use in primary care clinics and schools in other settings. From the outset, the design of this study involved the input of adolescents themselves, primary care clinicians and policymakers in health and education sectors during a stakeholder workshop. Throughout the grant's duration, stakeholder input and co-production will characterise the study through theory of change workshops and an advisory board. The study seeks to assess adolescent primary health care in six clinics and twelve schools in the Western Cape province of South Africa through a facility questionnaire to determine various aspects of adolescent healthcare services and the clinical characteristics of adolescents using these services. We shall observe the processes that adolescents follow to receive health care, including their consultations with clinicians. Focus group discussions with school and clinic managers, clinicians, community-based organisations, policymakers and adolescents will provide a broad understanding of existing adolescent health care. We shall then refine the PACK Adolescent guide and training programme following a theory of change workshop (a workshop intended to develop a system of ideas to explain how we think change happens in the area we want to address, and how we intend to work to influence these changes) with key stakeholders. The adapted intervention will then be piloted and evaluated in the six clinics and twelve linked schools (primary and secondary). Through observations of the use of PACK Adolescent and resultant changes to the clinical pathway for adolescents as well as interviews with adolescents, clinic clinicians and school health nurses we will see how PACK Adolescent meets the needs of adolescents and clinicians along with the challenges to its use. A survey questionnaire completed by clinicians in schools and clinics along with routine health data will help us to assess its impact. The outcomes of the study will provide an understanding of adolescent primary healthcare across schools and clinics. It will allow us to identify the minimum system strengthening components needed to support adolescent healthcare in an integrated way in both health and education sectors. We shall share these outcomes with participating schools and clinics, as well as the Departments of Health and Education in the province and nationally. They will inform the design of a future study evaluating whether PACK Adolescent leads to improved outcomes for young people.