T he past decade has seen a rise in research and clinical writings on therapist expertise (Hill et al., 2017;Tracey et al., 2014), resulting in a renewed interest in training practices to develop and enhance the clinical effectiveness and expertise of trainees and practicing therapists. Empirically, research has demonstrated that therapist expertise is not a result of merely accumulating experience doing therapy (Goldberg et al., 2016). For example, Goldberg et al. ( 2016) examined changes in clinical outcomes for 6,591 clients receiving individual therapy from 170 therapists over a 5-year time period. Therapists' outcomes did not significantly improve as therapists gained experience, as measured by chronological time or cumulative patients seen. The growing acknowledgement of the absence of an expertise-experience relation has resulted in various propositions of the necessary conditions to facilitate trainee and therapist development. For example, Tracey et al. (2014) proposed that high-quality outcome feedback was necessary to develop therapist expertise. Others have noted the importance of experience with clients, personal therapy, supervision, and feedback (Hill et al., 2017).