Tanzanian enterprises operate within a complex institutional environment characterised by infrastructural deficits, regulatory fluidity, and capital market inefficiencies. Existing business diagnostics often fail to capture the dynamic interplay between these structural constraints and firm-level strategic responses, creating a gap in actionable frameworks for long-term adaptation. This working paper develops and presents a diagnostic framework to analyse how firms identify, prioritise, and navigate persistent structural constraints. It aims to delineate the mechanisms of strategic adaptation and evaluate their efficacy for sustaining enterprise growth and resilience. The study employs a longitudinal, multi-case design synthesising archival data, policy analysis, and structured interviews with senior executives from a stratified sample of firms across manufacturing, agribusiness, and services. The analytical process involved iterative pattern matching between observed strategies and constraint typologies. A predominant theme was the strategic internalisation of logistics and energy generation, with over 60% of sampled firms investing in private power solutions. The framework identifies a critical pivot from reactive coping towards proactive capability-building as a key differentiator in enterprise performance. Structural constraints, while binding, can catalyse innovation and strategic renewal when firms employ systematic diagnostic processes. The proposed framework elucidates the pathways from constraint recognition to embedded adaptive capacity. Enterprise leaders should institutionalise regular constraint audits. Policymakers ought to design interventions that support, rather than supplant, the adaptive strategies firms are already developing, particularly in energy and supply chain logistics. strategic adaptation, structural constraints, diagnostic framework, enterprise resilience, business environment, East Africa This paper provides a novel diagnostic framework that integrates institutional economics with strategic management theory, offering a structured tool for analysing firm-level adaptation to systemic constraints in emerging markets.