Introduction: People who belong to a sexual and gender minority often faceprejudices that have their roots in heterosexism, a sociocultural system thatcan manifest itself in different ways and sometimes in a seemingly benevolentfashion. The present study examined the psychometric properties of theMultidimensional Heterosexism Inventory (MHI), a scale assessing aversive,amnestic, paternalistic, and positive stereotypic heterosexism, in an Italiansample.Methods: Two hundred one cisgender and heterosexual individuals (129 womenand 72 men) aged 18 to 81 years (M = 36.42,SD = 12.56) were recruited online betweenMay and October 2022 and answered questions about social dominance orientation,right-wing authoritarianism, ambivalent sexism, and attitudes toward lesbiansand gay men.Results: Confirmatory factor analysis showed that the original 4-factor modelof the scale fit the data well. Predictive and convergent validity of theItalian version of the MHI was adequate, whereas discriminant validity was notfully achieved due to overlap of multidimensional heterosexism with hostile andbenevolent sexism and authoritarianism. Scores were higher for aversive andamnesic heterosexism in men than in women, but not for paternalistic andpositive stereotypic heterosexism. Finally, less educated participants, thosewith no LGBTQI + friends, and religious participants were higher in all MHIsubscales than their counterparts.Conclusions: This study provides the first evidence for the validity andreliability of an Italian version of the MHI.Policy Implications: Using the MHI can help to make visible not only the explicit butalso the subtle forms of heterosexism, thus recognizing the multidimensionalnature of heterosexism produced in social institutions.