We investigated the prevalence, patterns, and correlates of past‐year DSM‐IV hallucinogen use disorders (HUDs) among past‐year users of MDMA and other hallucinogens from a sample of Americans 18 or older (n = 37,227). Users were categorized as MDMA users and other hallucinogen users. Overall, one in five (20%) MDMA users and about one in six (16%) other hallucinogen users reported at least one...