The NIMH has made it a priority to strengthen the public health impact of evidence-based practices (EBPs), including identifying and supporting means by which EBPs are broadly disseminated and implemented1. The number of efficacious treatments is growing, but most are slow to make their way into standard practice2, im- peding the impact of scientific discoveries on public health and leaving millions of Americans without access to the best available treatments3. One of the key barriers to the dissemination and implementation of EBP in rou- tine care is the lack of effective training opportunities available4. Most current training is focused on entire treatment packages, often based on manualized protocols developed for efficacy trials5. Training of this kind can be expensive, time-consuming, and relatively less successful in implementation6,7 . Modular web-based training (WBT) in evidence based change processes holds great promise for individu- alization of treatment linked to specific client needs, which might both simplify the dissemination process and ensure an appropriate role for client preferences and values8. Modular training of core change processes efficiently trains providers to implement the most effective elements of an empirically supported treatment9-11 and allows for flexible and adaptive use of EBPs, factors known to improve implementation12,13. WBT is efficient, inexpensive, widely accessible, and shown to work as well or better than current standard training practices 5,14,15. Two change processes that are common across several empirically supported treatments are cognitive de- fusion and values. These are prime candidates for modular training as they are 1) implicated in a range of mental health problems16-20, 2) amenable to brief interventions that can be implemented by any kind of mental health provider in any service setting21, 3) shown to produce large effect sizes on diverse clinical outcomes, even with very brief interventions16,22-34, and 4) are compatible with many other EBPs, thus increasing their ac- ceptability, feasibility, and sustainability35-39. Though theoretically promising, little is known about how best to implement modular web-based training and how it impacts therapist practices and client outcomes. That is a key focus of the present project. The proposed randomized controlled study will examine the impact of a brief WBT on treatment fidelity and client outcomes, two key outcomes recommended by Fixsen and colleagues'comprehensive Stages of Implementation model40,41. 30 therapists will be randomly assigned to a wait list or immediate WBT in either de- fusion or values procedures. The wait-list will control for effects of time and repeated measurement, and the two active training conditions will control for non-specific training effects. Following training, each therapst will conduct 3 sessions of the trained procedures with 2 clients. Client measures of treatment process and out- come will be collected weekly during baseline, treatment, and follow-up phases and analyzed using multi-level modeling. Therapist measures of treatment fidelity and acceptability will be assessed at pre-, post-, and 1- month follow-up and analyzed using multilevel modeling, and will be explored as moderators of client changes. Successful implementation requires organizational level support42-43 and even though intervening at this level is beyond the scope of the current study, we plan to assess organizational factors that may influence implementation using theoretically derived and psychometrically validated measures to inform future studies. PUBLIC HEALTH RELEVANCE: One of the most important issues in mental health services research is the gap between our knowledge of effective treatments and delivery of those treatments in routine care. The number of efficacious treatments is growing, but most are slow to make their way into standard practice2, impeding the impact of scientific discoveries on public health and leaving millions of Americans without access to the best available treatments3. The NIMH has made it a priority to strengthen the public health impact of evidence-based practices (EBPs), including identifying and supporting means by which they are broadly disseminated and implemented1, but there remains a paucity of research on the efficacy of dissemination and implementation of EBPs . One of the key barriers to the dissemination and implementation of EBP in routine care is the lack of effective training opportunities available4. The current study could increase the impact of EBPs on public health by identifying an efficient and effective dissemination strategy that will increase access to best available treatments.