Abstarct: This grounded theory study, following Corbin and Strauss's (2015) systematic methodology, investigated the challenges Iranian public high school English teachers face and their adaptive strategies. Through theoretical sampling, twelve teachers (6 male, 6 female; 3-15 years' experience) were selected for open-ended interviews, supplemented by policy document analysis (MOE, 2022). The study employed constant comparative analysis across three coding phases: open coding identified 78 initial concepts (e.g., "resource improvisation"), axial coding revealed relationships between categories using the paradigm model (causal conditions, strategies, consequences), and selective coding integrated findings around the core category of "negotiating disempowerment." Theoretical saturation was achieved after 12 interviews, with memo-writing maintained throughout to track analytical decisions. The analysis identified five interconnected thematic categories constituting the core phenomenon: (1) systemic barriers (overcrowded classrooms, outdated resources, infrastructure deficits), (2) student-related challenges (mixed proficiency levels, low motivation), (3) teacher demotivation (inadequate training, administrative pressures, economic precarity), (4) cultural/political disconnect (family attitudes, ideological resistance), and (5) assessment and policy failures (exam-centric system, lack of accountability). The core process of negotiating disempowerment explains how teachers employ regulated improvisation—developing hidden adaptations while maintaining surface compliance—revealing a form of agency distinct from Western autonomy models. Methodologically, the study demonstrates how Corbin and Strauss's approach effectively uncovers systemic dynamics in restrictive educational contexts. Theoretically, it contributes the concept of "fractured professionalism" to describe teachers' dual identities in authoritarian systems. Practical implications highlight needs for policy alignment (e.g., matching assessments to curriculum) and formalizing teacher support networks. Findings challenge deficit narratives by documenting teachers' strategic resilience amid constraints, offering insights for similar centralized education systems.