This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:To identify and evaluate the effectiveness of interventions for preventing repeat unintended pregnancies among adolescents, and to determine the barriers and facilitators for their implementation and uptake. Specific review question are to determine: What are the barriers and facilitators to the acceptability, uptake and implementation of interventions? What factors characterise subgroups who are at greater risk of repeat unintended pregnancies (i.e. what are the predictors of repeat unintended pregnancy)? Which (elements of) interventions appear to be effective, how do they work, in what setting and for whom (conversely, why are they ineffective, why do they not work)? What evidence is there on the relative cost‐effectiveness of interventions to prevent teenage pregnancy? What specific methodological challenges does application of health economics to this area raise and how are these challenges being overcome?