This chapter applies the Innovation Systems from Below (ISFB) framework to analyse how innovation emerges through the mechanisms of strategic coupling and institutional bridging. Drawing on empirical case studies of four lead firms (Embraer, Natura, Cemex, and Volkswagen de México) and two technology parks (BH-Tec and PIIT), the chapter develops a mechanism-based explanation to uncover how firms and intermediary institutions access, mobilise, and integrate innovation-relevant knowledge. Strategic coupling is examined as a dynamic, actor-led process whereby firms form purposeful linkages across diverse knowledge sources, channels, and geographies. Institutional bridging, in turn, highlights the agency of non-firm actors in connecting firms to wider innovation infrastructures and facilitating systemic upgrading. Through comparative analysis of Brazilian and Mexican contexts, the chapter identifies situational, action-formation, and transformational mechanisms that shape innovation outcomes at multiple levels. The findings underline the role of competence-building, institutional alignment, and regional learning in enabling innovation under conditions of institutional incompleteness or fragmentation. The ISFB framework thus serves as both an analytical and a practical tool for understanding how innovation systems evolve from below, offering insights for research, policy, and organisational strategy in emerging and developing economies.