This essay takes up the issue of anal sexuality among gay men in order to consider the relationship between bodily and psychic penetrability. The lack of recognition some gay men may experience with this aspect of their sexuality suggests the importance that feeling “mentalized” (e.g., Fonagy and Target, 1993) may play in adult life. Drawing on early gay liberation and ACT UP-era theorizing about anal sex and an extended clinical example, I explore the meanings of gay men's wishes to (and fears of) penetrate and be penetrated on both bodily and psychic levels as well as the consequences of feeling denied entry. My consideration of these matters becomes in turn an occasion for a critical assessment of the mentalization concept itself.