This article introduces the Beliefs about and Attitudes toward Menstruation Questionnaire (BATM). It is a 5-point Likert scale that was normed on 1,090 Mexican people of different ages and educational levels. In a second study data from 274 undergraduate students from Mexico and the United States were compared. Four factors emerged in both samples: secrecy, annoyance, proscriptions and prescriptions, and pleasant. Mexican students scored significantly higher than U.S. students on the Proscriptions and Prescriptions subscale. Men scored significantly higher on this subscale than women. Implications of these findings are discussed, as is the possible utility of the questionnaire for future research.