Child welfare providers are increasingly required to demonstrate that strengths-based, evidence-informed practices are central to their intervention methodology. This case study describes how a large child welfare agency instituted cognitive behavioural therapy (CBT) as the core component of a strength-based practice model with the goal of developing a unifying methodology for treatment and intervention across diverse programmes that range from community-based counselling to wraparound to acute residential care. One factor that aided implementation was that many agency staff had previously been using a variety of strengths-based tools, such as therapeutic crisis intervention, skills-based training, solution-focused therapy, and relaxation techniques in their work with children and youth. Challenges included creating a common training curriculum about CBT, trauma-focused CBT, and solution-focused therapy for hundreds of diverse staff; implementing ongoing support in the form of supervision and training; managing staff members' other theoretical orientations and some resistance to change; and developing documentation to integrate CBT into clinical assessments, progress notes, and service plans. This paper also describes the evaluation plan to assess fidelity to the practice model, including trauma-focused CBT practice checklists, a revised utilisation review process to assess documentation of strengths-based interventions in case records, and the use of functional assessments to measure client outcomes.