Although various authorities have found that sexual orientation and gender identity have no relationship to workplace performance, during the past four decades a large body of research using a variety of methodologies has consistently documented high levels of discrimination against lesbian, gay, bisexual, and transgender (LGBT) people at work. This chapter reviews recent research regarding such discrimination as well as regarding the effects of such discrimination on LGBT people. The latter research shows that discrimination has negative effects on LGBT people in terms of health, wages, job opportunities, productivity in the workplace, and job satisfaction. Widespread and continuing employment discrimination against LGBT people has been documented in scientific field studies, controlled experiments, academic journals, court cases, state and local administrative complaints, complaints to community-based organizations, and in newspapers, books, and other media. Further, federal, state, and local courts, legislative bodies, and administrative agencies have acknowledged that LGBT people have faced widespread discrimination in employment. Results from all of these sources are discussed below.