Pharmacologic methods of treating and preventing HIV have advanced tremendously in recent years. Understandings of HIV risk and recommendations for risk-reduction strategies have also changed substantially. A majority of new cases of HIV in many developed countries are now acquired through sex with long-term partners who are unaware of their HIV-positive status, rather than from casual or anonymous sexual encounters. Persons with bipolar disorder and substance use disorders are at particularly high risk. Mental health providers who work with LGBT persons and other populations at higher risk for HIV need to understand strategies their patients are using for HIV risk reduction, and to refer appropriate patients for consideration for pre-exposure prophylaxis (PrEP). PrEP is the daily use of an antiretroviral (ARV) medication for prevention of HIV infection in higher-risk individuals. The United States approved tenofovir + emtracitabine for PrEP in 2012; this is under review in several European countries, Canada, and Australia, and is already prescribed off-label in many. Additionally, studies have shown that treatment with ARV medications to an “undetectable viral load” greatly reduces the risk of further transmission by persons already infected with HIV, called “treatment as prevention” (TasP). As of September 2015, WHO recommends early ARV treatment for all persons with HIV, and consideration of PrEP for men who have sex with men. This paper reviews findings from the PrEP studies (especially iPrEx, iPrEx Ole, IPERGAY, and PROUD) and TasP, and looks at their impact on LGBT and HIV+ communities, with relevance for mental health providers.