Abstract With a surge in critiques levelled against the evidence generated by randomised controlled trials in the study of psychedelic-assisted therapy (PAT), and the legalization of PAT in select jurisdictions such as Australia, and Oregon and Colorado in the United States, we consider what form the real-world evidence of its effects could take. Specifically, we propose to complement individual-level data-gathering (the usual remit of pharmacovigilance procedures) with evidence of PAT's collective effects. Taking our cue from long-standing claims that psychedelics are agents of social transformation, we draw upon the ‘transformative paradigm’ of evaluation, an approach that is itself oriented around social justice and change vis-à-vis marginalised expertise – or what we approach as ‘the grassroots’. To illustrate the potential of such grassroots evaluations, we offer eight examples of social issues that have been discussed in relation to PAT and psychedelics use and, for each, discuss the kinds of expertise that could be brought into the evaluation team and the kinds of questions that could be asked. We further describe our grassroots approach according to three values inspired by the qualities of grass roots themselves: rhizomatic accountability , dark reflexivity , and more-than-human hosting . We argue that these values align with the contemporary experience, practice, and context of PAT. We hope to generate discussion, innovation, and – ultimately – action toward specific study designs that are adequate to the task of documenting, and working with, the transformative potential of psychedelics in contemporary medicalized societies.
