As more individuals diverse in sexuality and gender are 'coming out,' it is becoming apparent that mental health professionals are lacking sufficient training in treating these populations. The difficulty in defining the various genders and sexualities, as well as reasons why training in the area of sexuality and gender diversity is needed for mental health professionals to ensure competency, are discussed in the introductory chapter. Historical background concerning socialization of the general population in regard to the gender binary and heterosexual norm then follows, including how social representations of sex, gender, and sexual orientation influence personal views and affect diverse individuals. Ten training modules are then presented that can be used to train mental health professionals in sexuality and gender diversity in order to help overcome some of these negative influences. The modules are intended to help professionals gain a deeper understanding of diverse individuals, explore personal stereotypes/personal biases, and facilitate the integration of the two in order to provide high quality, competent care.