Trans and nonbinary individuals experience high rates of identity-based stigma and stress (minority stress) in U.S. society. Despite research empirically linking minority stress with adverse mental health outcomes, the extent to which minority stress experiences are discussed in psychotherapy and how therapists respond is unknown. The primary aim of the present study was to develop and test an observational coding scheme, the Minority Stress Experiences and Interactions (MSEI) scheme. With this scheme, observational data from psychotherapy sessions with 19 transgender and nonbinary adult psychotherapy client participants were coded to provide pilot data for the initial development of the MSEI coding scheme. A total of 19 clients' entire 50-min psychotherapy sessions were coded over 3 phases of psychotherapy: beginning (Session 1), middle (Session 2), and end (Session 10/11). Results indicate that the MSEI scheme was reliable for most codes. Codes revealed that all (N = 19; 100%) clients in the study reported at least 1 minority stress event (MSE) over the course of the 3 sessions, with the mean number of MSEs being 7 per client. The most frequent proximal stressor reported by clients was related to internalized stigma and the most frequent distal stressor reported by clients was prejudice. A total of 2 clients' clinical exchanges with their therapists centered on MSEs are highlighted to demonstrate the nuance of how MSEs are discussed in session, specifically regarding multiple minority identities. Implications for the current study include the need for therapist training regarding minority stress interventions and attention to power and oppression within sessions. (PsycInfo Database Record (c) 2021 APA, all rights reserved).