This pilot study evaluated a body image intervention for men, Body Project M. Seventy-four British undergraduate men took part in two 90-min intervention sessions, and completed standardised assessments of body image, bulimic pathology, and related outcomes at baseline, post-intervention, and 3-month follow-up. Fifty-three other men completed the questionnaires as an assessment-only control group. Per-protocol analysis showed that Body Project M improved men’s dissatisfaction with body fat and muscularity, body appreciation, muscularity enhancing behaviours, appearance comparisons, and internalization (ds = 0.46–0.80) at post-intervention. All except dissatisfaction with muscularity and internalization were sustained at 3-month follow-up. No effects were found for bulimic pathology. Post-intervention effects for dissatisfaction with muscularity and internalization only were retained under intention-to-treat analysis. Participants were favourable towards the intervention. This study provides preliminary evidence for the acceptability and post-intervention efficacy of Body Project M. Further development of the intervention is required to improve and sustain effects.