Trauma-informed evidence-based treatments for the youngest children are insufficiently and unevenly implemented, and access to effective interventions for young children and their families is scarce in Sweden and internationally. Child-parent psychotherapy (CPP) is one of only a few treatment models for trauma-exposed children under the age of 6 years. The aim of this study was to explore the extent to which clinicians trained in CPP continued to work with the model after training and how they experienced its implementation and sustainability over time. We distributed a survey to all 66 clinicians in Sweden trained in CPP and conducted qualitative interviews with a sample of 12 from various organizations.About two of three clinicians continued to work with the model post training, but few had treated enough cases to have acquired extended experience or expertise. Using a mixed methods model including thematic analysis, we identified four main themes (three with two subthemes): Work with trauma-exposed young children (sub-themes “Clinicians’ access to young trauma-exposed children” and “Complexity in providing services to trauma-exposed children”); Organizational and systems level aspects (sub-themes “Sociopolitical decisions, unclear responsibilities, and other external conditions” and “Like running my own little business—the clinician within the organization”); Support to deliver child-parent psychotherapy” (sub-themes “Collegial support—it makes all the difference” and “Continued learning and fidelity—the importance of methodological support to deliver the CPP model”); and The clinician and Child-Parent Psychotherapy” (no subthemes). Implementation and sustainability of the CPP model seemed to be both facilitated and hindered by interplay among systems-level, within-organization, and individual factors. The simultaneous need of treatment for young children affected by trauma and the lack of access to such treatment is particularly worrying.