Abstract
This chapter provides an overview of how individuals form impressions about others' sexual orientation and their consequences on stigma and discrimination. People often form these impressions based on subtle cues, such as facial features or vocal characteristics. Research suggests that the perception of sexual orientation is based on the assumption that everyone is heterosexual unless cues indicate otherwise. Such cues, which suggest a lesbian or gay orientation, are often linked to perceived gender non-conformity, which can lead to accurate impressions in some cases but may be incorrect in others. Regardless of their self-identified sexual orientation, individuals perceived as lesbian or gay are at risk of discrimination (i.e., discrimination by perception). Individuals perceived to be lesbian or gay are often associated with gender non-conforming characteristics and are more likely to face avoidance, exclusion, and discrimination across various contexts (e.g., workplace). Discrimination by perception represents a modern form of prejudice that can be difficult to challenge, but promising intervention strategies provide potential solutions to address this issue.