Objective: The aim of this study was to conduct a preliminary dismantling study of exposure, relaxation, and rescripting therapy (ERRT) for nightmares. Method: Participants (N = 70) were randomized to 1 of 2 conditions: ERRT with nightmare exposure and rescripting (full protocol; EX) or ERRT without nightmare exposure and rescripting (NEX). Participants completed follow-ups at 1 week, 3 months, and 6 months posttreatment. Results: Both conditions yielded statistically significant improvements with medium to large effect sizes on primary outcomes related to nightmares (i.e., nights with nightmares, nightmares per week, and nightmare severity). Both conditions also yielded statistically significant improvements on secondary outcomes with medium to large effect sizes on fear of sleep, sleep quality, insomnia severity, daytime sleepiness, posttraumatic stress disorder symptom severity, and depression severity. The conditions did not differ at any time point. Conclusions: Findings indicate that ERRT with and without nightmare exposure and rescripting can significantly alleviate nightmares and related distress. The addition of nightmare exposure and rescription did not contribute incrementally to outcomes in this sample. It is possible that the dose of exposure was not sufficient to result in group differences or that the treatment components included in both conditions (i.e., psychoeducation about trauma, nightmares, and sleep; sleep habit modification; and relaxation training) may adequately treat factors that maintain nightmares for some individuals. Theoretical implications of findings are discussed. The reduction of symptoms of other conditions following this brief intervention provides further evidence for the primary role of nightmares and sleep disturbances posttrauma.