The American Psychiatric Association (APA) was the primary organization that classified homosexuality as a mental disorder in its official diagnostic manuals for several decades. The classification was as follows:
DSM-I (1952): Homosexuality was listed as a "sociopathic personality disturbance".
DSM-II (1968): Homosexuality continued to be listed, but was reclassified under the category of "personality disorders" as a "sexual deviation".