Although homosexuality was depathologized in the last century and the majority of mental health professionals consider it to be a normal variant of human sexuality, some psychologists and psychiatrists still have negative attitudes toward lesbian, gay and bisexual (LGB) clients. Sometimes they provide interventions aimed at changing sexual orientation through 'reparative' or 'conversion' therapies. At other times their interventions are influenced by anti-gay prejudices or simply by lack of knowledge about sexual minorities. This paper argues for the need for appropriate treatment guidelines aimed at providing bias-free, respectful, and effective interventions given that Italian health associations have delayed providing them. Some of the main guidelines recently approved by the Consiglio Nazionale dell'Ordine degli Psicologi (National Council of the Italian Association of Psychologists) are presented. Issues addressed include differences between gender and sexual orientation, minority stress, including perceived stigma and internalized stigma, homophobic bullying, coming out, and resilience. Respectful listening to LGB and questioning clients, affirming their identities and fostering a sense of resilience are essential requirements for all mental health professionals wishing to provide effective interventions in a society where sexual minorities are subjected to discrimination throughout their entire life cycle.