Peer-based youth services provided by small non-profit community organisations have grown in number over the past two decades in response to an increasing need for informal, youth-friendly, accessible and confidential early intervention services. However, gaps in the evidence base and a general lack of evaluation capacity of service providers limits the validation of program benefits and threatens program sustainability. This paper reports on the development of a practitioner-centred, free online resource, the My-Peer Toolkit [1.0], which provides theory-based and practice-based guidelines for planning, implementing and evaluating peer-based youth services. An important secondary outcome of the participatory action research design used in this study was building practitioners' capacity to evaluate and deliver services and to develop solutions to local issues. (Contains 1 figure and 2 tables.)