Abstract: Political regime transitions in Sub-Saharan Africa (SSA) exhibit a pronounced bifurcation between peaceful transformation and violent upheaval, yet conditions and causal mechanisms for stable, nonviolent change remain scant, partly due to pervasive treatment of structural and agency factors in isolation. This study advances an integrative, qualitative comparative framework that elucidates how individual political agency and structural dynamics interact to produce divergent outcomes, using Ethiopia and Sudan as focal cases. It synthesizes leadership trajectories, coalition architecture, and socio-political ecologies to trace how leadership turnover, party organization, and state–society relations converge to foster stability or provoke volatility. Ethiopia’s episodic leadership changes within a relatively cohesive ruling coalition, reinforced by a reformist orientation and functional parliamentary mechanisms, facilitated continuity and negotiated reform, while Sudan’s extended tenure, succession ambiguity, and shift toward centralized rule undermined legitimacy, intensifying civil–military contestation amid economic distress. By foregrounding mechanisms through which individual traits (ambition, inclusivity, legitimacy-building capacity) interact with institutional configurations (coalition coherence, reform and ideological reorientation, power-sharing norms) and broader context (economic pressures, diaspora mobilization, international scrutiny), the analysis demonstrates that peaceful transitions emerge from nested interactions across levels rather than any single dimension. The study concludes with policy implications for integrated strategies that bolster inclusive governance, institutional resilience, and adaptive leadership in SSA, advocating holistic reform over siloed interventions. Keywords: Political Regime Transition, Comparative Case Study, Agency, Structure, Ethiopia, Sudan