Crossover youth, those involved in both the child welfare and youth justice systems, are more likely to receive detention and harsher sentences than youth with no child welfare involvement. In Ontario, the Crossover Youth Project (COYP) was formed to ameliorate these systemic issues. To evaluate the success of a Toronto pilot site, a convergent parallel mixed methods study was completed. A total of 19 stakeholders, mostly from youth justice and child welfare, were interviewed at the closure of the pilot and 15 nine months later. Interviews were analyzed qualitatively using thematic analysis and interpreted alongside quantitative data from questionnaires. Themes indicate that stakeholders’ knowledge of crossover youth and skills in advocacy increased, as well as their ability to collaborate. While their learning was maintained at follow-up, their ability to collaborate was impaired by loss of the case coordinator who was essential to facilitating conferences. Results can inform future interventions.