Hybrid work, which blends office and remote flexibility, presents both challenges and opportunities for organisations aiming to support employee-driven innovation (EDI). In this thesis, EDI is operationalised as innovative work performance (IWP), reflecting employees’ proactive generation and implementation of ideas in everyday work. Despite widespread adoption, its impact remains unclear, often resulting in ineffective policies. This thesis aims to examine how hybrid work conditions shape employees’ social capital, knowledge sourcing behaviours, and ultimately IWP. Hybrid work conditions are operationalised using the of structural (Remote Intensity), technological (Digital Information Communication Quality), and spatial (Task Virtuality), influence employees’ social capital and knowledge sourcing behaviours, and how these contribute to IWP. It also introduces the Hybrid Relational Communication Ratio (HRCR), an MRT-informed construct that captures the balance of face-to-face and technology-mediated communication across hybrid settings. HRCR was developed following a scoping review that identified conceptual and methodological gaps in existing MRT-based operationalisations for understanding hybrid communication quality. These hybrid work conditions are examined across three studies. Study 1 evaluates the predictive utility of MRT-based measures and HRCR for cognitive, relational, and structural dimensions of social capital. Study 2 examines how HRCR moderates the social capital-IWP relationship. Study 3 applies the Task Virtuality construct to test how hybrid conditions moderate the relationship between knowledge sourcing and IWP. Using cross-sectional surveys across three organisations, Study 1 (N = 141; approximately 846 alters, defined as individuals in participants’ personal networks) found that lower HRCR scores (indicating richer communication) were associated with stronger social capital. Study 2 (N = 204; approximately 1,224 alters) found that HRCR moderated the negative social capital-IWP relationship. Study 3 (N = 102) showed that knowledge sourcing supported innovation at specific levels of task virtuality. Findings demonstrate that communication quality influences how employees engage with social capital and knowledge sourcing behaviours, and, under certain conditions, can buffer the effects of communication strain in supporting innovation. HRCR offers a practical lens for evaluating communication quality in hybrid contexts. Together, these studies extend media richness theory into hybrid work environments and clarify how communication conditions shape the social and knowledge practices that underpin employee-driven innovation.