Most early work on high performance work systems (HPWSs) examines only the direct relationship between a set of management practices and performance outcomes and seldom investigates the “black box” between them. Although recent studies tried to examine the mechanism, the main perspective was to discuss individual outcomes, or simply aggregated individual outcomes. On top of the previous individual approach, this conceptual work takes a group level approach and investigates how the HPWS may change the organizational effectiveness through changing the organization's intra-organizational social capital. Implications and contributions are also discussed.