A new model of therapist skill development is presented. Grounded in information processing theory, it provides a comprehensive framework that accounts for a range of phenomena encountered by trainers and trainees – for example, why different training methods are needed for different elements of therapist skill. The model features three principal systems: declarative, procedural and reflective (DPR). Reflection is identified as central to therapist skill development and, accordingly, a pivotal role is given to a reflective system, which enables therapists to reflect and build on their conceptual (declarative) knowledge and procedural skills. The DPR model incorporates a taxonomy of therapist skills, and explains why different skills develop in different ways at different rates. It highlights the centrality of therapists' perceptual skills, and of when-then rules, plans, procedures and skills (rules that determine when to implement what interventions with which patient under what conditions) in the development of therapist expertise. It makes a distinction between personal and professional selves (the self-schema vs. the self-as-therapist schema); and it identifies the role of the personal self in therapist skill development. While there are still many questions to be investigated, it is hoped that the model will stimulate researchers and provide guidance for trainers.