This study reports on the initial development and validation of the Teacher Subjective Wellbeing Questionnaire (TSWQ) with 2 samples of educators--a general sample of 185 elementary and middle school teachers, and a target sample of 21 elementary school teachers experiencing classroom management challenges. The TSWQ is an 8-item self-report instrument for assessing teachers' subjective wellbeing, which is operationalized via subscales measuring school connectedness and teaching efficacy. The conceptualization and development processes underlying the TSWQ are described, and results from a series of preliminary psychometric and exploratory analyses are reported to establish initial construct validity. Findings indicated that the TSWQ was characterized by 2 conceptually sound latent factors, that both subscales and the composite scale demonstrated strong internal consistency, and that all scales demonstrated convergent validity with self-reported school supports and divergent validity with self-reported stress and emotional burnout. Furthermore, results indicated that TSWQ scores did not differ according to teachers' school level (i.e., elementary vs. middle), but that they did differ according to unique school environment (e.g., 1 middle school vs. another middle school) and teacher stressors (i.e., general teachers vs. teachers experiencing classroom management challenges). Results also indicated that, for teachers experiencing classroom challenges, the TSWQ had strong short-term predictive validity for psychological distress, accounting for approximately half of the variance in teacher stress and emotional burnout. Implications for theory, research, and the practice of school psychology are discussed.