In Quebec, crossover youth refer to those who are monitored under the Youth Criminal Justice Act (YCJA) and have, at some point in their life, been under the care of the Youth Protection Act (YPA). Among the population served by Youth Centres (YCs), these young people are considered most vulnerable and are at risk of re-offending. Using descriptive and comparative analyses, this article presents an overview of the service trajectories of 15,851 crossover youth, from childhood through adolescence. It provides a detailed chronology of their care history and services they received under both Acts and highlights the issue of concurrent intervention. The results reveal four main trajectories that differ in terms of history of victimization and delinquency. The trajectory named child protection entry and YCJA overlap is the most frequent service trajectory; but is also one that is marked by the highest rates of infraction and recidivism. The trajectory called child protection entry and YCJA inclusion is composed of youth with the highest rates of reported maltreatment and the highest rates of placement instability but lower rates of recidivism. The implications for intervention in YCs, particularly in terms of coordinating juvenile justice and protection systems, are discussed.