We studied the mechanisms of eye movement desensitization and reprocessing (EMDR) and imagery rescripting (ImRs). We hypothesized that EMDR works via changes in memory vividness, that ImRs works via changes in encapsulated beliefs (EB), and that both treatments work via changes in memory distress. Patients (N = 155) with childhood-related posttraumatic stress disorder (Ch-PTSD) received 12 sessions of EMDR or ImRs. The vividness, distress, and EB related to the index trauma were measured with the Imagery Interview.