Nicolosi earned a
Master of Arts from the
New School for Social Research and a
Ph.D. from the
California School of Professional Psychology. He was a founding member of the
National Association for Research & Therapy of Homosexuality (NARTH) and was its president for some time. NARTH is a professional association that promotes the acceptance of
conversion therapy. He was an advisor to, and officer of, NARTH. NARTH was for some time based in Encino at Nicolosi's own "
Thomas Aquinas Psychological Clinic". According to the
Southern Poverty Law Center, "NARTH presents its methods as based on scientific fact rather than religious belief". Nicolosi was a
Roman Catholic. Scientific research, summarized in a 2016 academic review, has not supported Nicolosi's hypothesis that parents play a role in the development of sexual orientation, and social theories are particularly weak for males. Nicolosi gave an interview with the
BBC in order to defend his opinions, claiming: "we have a great deal of evidence". At the conference, Nicolosi performed "therapy" on a man live in front of the audience, a sight
Patrick Strudwick described as "like I was watching a
blood sport". In 2012, California passed a law that
banned the provision of conversion therapy to minors, including some of Nicolosi's existing patients. Nicolosi was named as a plaintiff in a
lawsuit challenging the law on constitutional grounds but the law, effectively barring Nicolosi's clinic from taking on patients under the age of 18, was subsequently upheld. The Supreme Court later explicitly referenced this case. In 2013, Nicolosi appeared in
Stephen Fry's television documentary
Stephen Fry: Out There, which examined different attitudes to homosexuality. Nicolosi informed Fry that "sixty percent of our clients now are teenagers. Parents call up in a panic because they found out their son is looking at gay porn, and, of course we have to get him into therapy". After the segment, Fry says that "for all his talk of success, Nicolosi is unable to find one of his ex-gays to talk to us". Fry then speaks with Daniel Gonzales, a former client of Nicolosi's who did not have success in changing his sexual orientation. Gonzales condemns the therapy. From 2013, protests were raised in Spain over the sale of three of Nicolosi's books titled:
I Want to Stop Being Gay (),
How to Prevent Homosexuality (), and
Gender Confusion in Childhood (). Major Spanish department store
El Corte Inglés was threatened with a boycott by the
United Left coalition over its stocking of the works, but continued to market them in 2014. Nicolosi died in March 2017 at the age of 70 from flu complications. On July 2, 2019, leading online book retailer
Amazon removed several of Nicolosi's books from their catalog, including the 2002 publication ''A Parent's Guide to Preventing Homosexuality'', following a
Change.org petition requesting that they do so. Nicolosi's
NARTH continues to exist as "The Alliance for Therapeutic Choice and Scientific Integrity", headed by his son Joseph Nicolosi Jr. Nicolosi Jr. coined the term "reintegrative therapy" for his own approach which he says is distinct from conversion therapy. ==Effectiveness==