Charles Silverstein, who helped remove homosexuality from the American Psychiatric Association’s list of mental illnesses and coauthored The Joy of Gay Sex, has died at age 87. Silverstein’s death was announced on Twitter by Association for Behavioral and Cognitive Therapies. He died Monday, the organization said. He was a native and longtime resident of New York City. Silverstein’s first career was teaching elementary school, but in the 1970s he earned a Ph.D. in psychology and opened a private psychotherapy practice, according to Outwords. That was a pivotal decade for him in many ways. In 1973, his presentation helped persuade the APA to remove homosexuality from its Diagnostic and Statistical Manual of Mental Disorders.