["Addiction, EarlyView. ", "\nAbstract\n\nBackground and aims\nAustralia recently down‐scheduled and authorised psychedelic‐assisted therapies, including psilocybin, for certain mental health conditions. Evidence is emerging for potential application in substance use disorder treatment. However, regulatory developments have outpaced implementation readiness. While service leaders and clinicians are crucial to implementation, little research examines their perspectives on what psilocybin‐assisted therapy is, how it works, and for whom. This study explored how these stakeholders conceptualise psychedelic‐assisted therapy within their own professional setting, in the context of a broader implementation trial of psilocybin‐assisted therapy for co‐occurring depression and alcohol use disorder (AUD) in a routine alcohol and other drug (AOD) clinic.\n\n\nDesign\nA qualitative approach informed by the evidence‐making intervention approach.\n\n\nSetting\nVictoria, Australia, prior to the implementation of psilocybin‐assisted therapy in routine clinical services.\n\n\nParticipants\nTwo focus groups were conducted: one with clinicians (n = 9; nursing, psychology, psychiatry, pharmacy, and peer support professionals) and one with health service leaders (n = 9).\n\n\nMeasurements\nFocus groups used a semi‐structured guide, consisting of open‐ended questions about understandings and perspectives on psilocybin‐assisted therapy for co‐occurring substance use and mental health problems. Verbatim transcripts underwent inductive thematic analysis, informed by the evidence‐making intervention approach.\n\n\nFindings\nThree enactments of psilocybin‐assisted therapy emerged: (1) treatment of last resort for treatment‐resistant conditions, which was emphasised by service leaders and aligned with regulatory frameworks; (2) tool to “unlock stuckness” in ongoing relational care when conventional therapies plateau, which was prominent among clinicians; and (3) catalyst for rapid progress applicable at any treatment stage. Clinicians emphasised the need for careful integration, robust support, and aftercare, alongside concerns about access and eligibility. Service leaders highlighted operational and ethical tensions within regulatory requirements. Both groups understood psilocybin‐assisted therapy as a complex intervention dependent on interplay between medication, therapist skill, client readiness, and care context.\n\n\nConclusions\nPsilocybin‐assisted therapy in Victoria, Australia is constituted through local implementation rather than existing as a singular intervention. Implementation approaches must be reflexive and adaptive, with attention to clinical and managerial dialogue, equity considerations, and contextual practice factors.\n\n"]