Family rejection and violence are often cited as reasons for lesbian, gay, bisexual, transgender, and questioning (LGBTQ) youth entering out-of-home care. Though no research study with foster youth has directly made this connection, research with youth experiencing homelessness indicates there may be some evidence for this theory. The Los Angeles Foster Youth Study was a one-time study conducted by the authors and their research team as part of their collaboration with the Recognize Intervene Support Empower initiative, a five-year cooperative agreement awarded to the Los Angeles LGBT Center. The chapter estimates that 8.3% of young adults in the general population are LGBT. It demonstrates that questions about sexual orientation and gender identity can be asked among foster youth specifically, as they have for decades in large-scale general population research. The chapter highlights a major gap in the field of child welfare research – the absence of administrative data on sexual orientation and gender identity.