Implementation of evidence-based practices (EBPs) is highly encouraged within mental health services. This single case study examines the process of an EBP implementation effort, guided by the National Implementation Research Network (NIRN) implementation model, from the perspective of behavioural healthcare managers in a child and youth mental health provider organization. Qualitative methods identified process themes emerging over 3 years of an organizational change process that support and refine the NIRN model. Dedicated management oversight and implementation teams are essential for EBP implementation; practice leads and practice coaches are useful implementation innovations; and organizations seeking to implement several EBPs simultaneously must guard against organizational absorptive capacity. These findings can guide EBP implementation in child and youth behavioural healthcare.