The current study tested a conceptual model based on social-cognitive theory (Bandura, 1986), highlighting the influence of attitudes toward sexual minority individuals, training hours, affirmative counseling self-efficacy, and beliefs about affirmative practice on therapist engagement in lesbian and gay affirmative practice. We recruited via the Internet 443 heterosexual psychologists (n = 270), clinical social workers (n = 110), and marriage and family therapists (n = 63) residing in various parts of the United States. The majority of participants identified as female (70%) and White (88%). A path analysis indicated that beliefs and affirmative counseling self-efficacy mediated associations between attitudes and therapist engagement in affirmative practice. Furthermore, self-efficacy mediated the relation between training hours and engagement in affirmative practice. Results suggest that more affirmative attitudes are linked with higher levels of affirmative counseling self-efficacy and more positive beliefs, which in turn positively influences therapist engagement in affirmative practice. Additionally, more hours of training influence affirmative counseling self-efficacy, which in turn correlates with higher levels of therapist engagement in affirmative practice. The discussion includes implications for affirmative practice training.