Child sexual abuse (CSA) is a trauma that affects males in substantial numbers, sometimes in ways that are gender-specific (e.g., compromised masculine identity, confusion regarding sexuality). Much of the identification of the male-specific outcomes has been derived from practitioner experience and small qualitative studies. The current study explores gender-specific outcomes and describes the development of a scale to measure the effects of CSA on men. First, qualitative interviews with 20 men who were sexually abused in childhood were thematically analyzed. The emergent themes of sexuality, self-concept, psychological and emotional well-being, and social functioning were used to construct a 30-item instrument which was later completed by 147 men with histories of CSA. The dimensionality of the 30 items was then assessed for suitability as scales using confirmatory factor analysis (CFA). The final instrument, the Male Sexual Abuse Effects Scale (MSAES), combines three subscales: Negative Identity, Guilt and Self-Blame, and Psychological and Emotional Well-Being. Items concerning masculine identity were shown to be valid in the scale. MSAES scores were compared with the General Health Questionnaire–28 (GHQ-28) and found to be significantly correlated. GHQ-28 clinical thresholds were applied to differentiate clinical from nonclinical cases; an independent-samples t test showed that the clinical cases from the GHQ-28 had high scores on the MSAES. The new scale has the potential to help clinicians and researchers identify men who have been severely affected by CSA and who should be of clinical concern.