Occasionally, a client reports they were unsuccessfully treated with eye movement desensitization and reprocessing (EMDR) therapy in previous treatments. In contrast, the same client was treated successfully with EMDR at other locations with different therapists. This chapter explores the difference between successful and unsuccessful treatment experiences with the same client. Believing the model always works when fidelity to the EMDR therapy protocol is maintained; it reviews what can be learned from the client’s reports. The chapter presents lessons learned from clients who compare EMDR effective treatment with their previous unsuccessful treatment experiences. Meta-analysis found that fidelity to the EMDR protocol produced greater treatment results. In every case, unsuccessful treatment results were the result of the therapists not following the EMDR protocol as taught in the standard EMDR basic training.