<p>This study sought to contribute to the minimal evidence on what boys across the United States learn about menstruation in and out of the classroom. Boys’ knowledge and understandings of menstruation may influence their own lives, shape the menstrual-related experiences of girls and women who they interact with, and contribute to ongoing menstrual stigma. We conducted a qualitative research study utilizing in-depth interviews with 22 Black and Hispanic adolescent boys and young men between the ages of 15 and 24 living in New York City. A semi-structured interview guide explored participants’ initial exposure to the topic of menstruation; menstrual education in school; social and media influences related to menstruation; and the ways in which participants’ menstruation-related perspectives shifted over time. Analyses revealed three main themes: (1) limited education and exposure to menstruation; (2) societal influences, media, and peer dynamics shape menstrual stigma; and (3) interpersonal and cultural shifts influence menstrual perceptions. Key findings include a need for earlier and improved delivery of formal education on the physical and social experiences of menstruation, and how positive messaging about menstruation in the media has the potential to encourage more open dialogue about menstruating. These strategies may help to reduce menstrual stigma and existing negative perceptions of menstruation. Additional research is needed with a broader diversity of adolescent boys and young men across the United States.</p>