Joseph Diehl, PhD, is a postdoctoral fellow in the Psychedelics and Contemplation Lab at McGill University, where he works with Drs. Kyle Greenway and Nicolas Garel, developers of the Montreal Model of ketamine-assisted psychotherapy for treatment-resistant depression. He received his PhD in clinical psychology from Duke University and completed his predoctoral internship at Weill Cornell Medicine/NewYork-Presbyterian. His clinical training includes DBT, behavioral activation, and mindfulness-based cognitive therapy, and his research examines the processes, such as mindfulness, perseverative thinking, and the therapeutic alliance, that help explain who benefits from psychedelic and ketamine treatments and why. His recent articles include a process-based therapy framework for psychedelic-assisted psychotherapy and of a study of the therapeutic alliance in MDMA-assisted therapy for social anxiety disorder, and he created the Montreal Model's first online clinician training module.