Objective: To investigate engagement in metacognitive acceptance and subsequent efficacy with respect to decreasing 2 risk factors for disordered eating, body dissatisfaction (BD), and negative affect (NA). Method: In a pilot experiment, 20 female undergraduates (Mage = 24.35, SD = 9.79) underwent a BD induction procedure, received acceptance training using brief written instructions, and were then assessed on engagement in the technique. In a second experiment in which acceptance training was enhanced through the use of video format and a guided experiential exercise, 80 female undergraduates (mean age = 23.59, SD = 8.98) were randomized to an acceptance or control group following the same BD induction. Outcome measures were taken at baseline, postinduction, and posttreatment and consisted of separate visual analogue scales for weight and appearance satisfaction and the NA subscale of the Positive and Negative Affect Scale. Baseline assessments included the Eating Disorder Inventory–BD, Difficulties in Emotion Regulation Scale, Ways of Coping Questionnaire, and the Five Facet Mindfulness Questionnaire. Results: Enhanced training significantly increased engagement in acceptance. Nonengagement was associated with NA, emotion regulation difficulties, and avoidant coping. Acceptance training significantly increased weight and appearance satisfaction and reduced NA relative to control, with no significant differences between those who did and did not engage. Intervention effects were moderated by mindfulness, emotion regulation difficulty, and avoidant coping. Conclusions: Findings provide clarification regarding engagement and lend further support for the utility of acceptance, with particular benefit identified for those “at risk” for emotion regulation difficulty. (PsycINFO Database Record (c) 2016 APA, all rights reserved)