Classic psychedelics produce altered states of consciousness that individuals often interpret as meaningful experiences. Across a number of human studies, when the participant-rated intensity of the overall drug effects are statistically controlled for, certain subjective effects predict therapeutic and other desirable outcomes. Underlying neurobiological mechanisms are likely necessary but not sufficient to confer full and enduring beneficial effects. We propose that the subjective effects of psychedelics are necessary for their enduring beneficial effects and that these subjective effects account for the majority of their benefit.