["Addiction, EarlyView. ", "\nAbstract\n\nBackground and aims\nThe intentional use of psychoactive substances to enhance sexual experiences, known as chemsex, is associated with human immunodeficiency virus (HIV) transmission, psychological distress and social isolation among gay, bisexual and other men who have sex with men (GBMSM). While research has predominantly focused on high‐income countries, gaps remain in our understanding of the dynamics in Eastern Europe and Central Asia, where structural homophobia, restrictive drug policies and limited healthcare access uniquely shape chemsex‐related risks. There is limited research on how chemsex engagement evolves over time. This study aimed to identify the stages of chemsex engagement and examine how social, psychological and structural factors shape transitions between these stages among GBMSM in Kazakhstan.\n\n\nMethods\nThis study is a secondary analysis of data from a cross‐sectional qualitative study conducted in Almaty, Kazakhstan, between July and September 2023. Twenty‐one GBMSM who had engaged in chemsex within the past 12 months participated in semi‐structured interviews lasting between 60 and 90 minutes. All participants reported using mephedrone and/or alpha‐PHP (α‐Pyrrolidinohexiophenone). Deductive reflexive thematic analysis, guided by Life Course Theory, was used to reconstruct chemsex trajectories from retrospective participant accounts.\n\n\nResults\nFive distinct themes related to different trajectory stages were developed. Initiation occurred through trusted social networks in intimate settings, taking the form of unplanned encounters that fulfilled emotional needs for connection and belonging. Maintenance was characterised by self‐imposed temporal and dosage limits; however, participants reported a decline in satisfaction with sober sex. Escalation involved a breakdown of protective boundaries, an increased frequency and quantity of use and a deeper involvement in chemsex social networks, despite mounting physical and psychological consequences. Dependence was characterised by a narrowed agency under escalating constraints, with substance use shifting from enhancing pleasure to coping with withdrawal, resulting in substantial impairment across life domains. Disengagement attempts described recursive trajectories with diverse recovery goals ranging from cessation to managed use. Sustained abstinence was rare and dependent on affirming care and supportive resources. Throughout all stages, structural stigma constrained individual agency, while chemsex networks provided crucial emotional safety that was unavailable in mainstream environments.\n\n\nConclusions\nChemsex trajectories among gay, bisexual and other men who have sex with men in Kazakhstan represent dynamic processes shaped by the interaction between individual agency and structural constraints, in which substance use functions as an emotional regulation strategy and a social survival strategy in contexts of high stigma.\n\n"]