This study examines major theory developments in human resource (HR) fields and discusses implications for human performance technology (HPT). Differentiated HR fields are converging to improve organizational performance through knowledge-based innovations. Ruona and Gibson (2004) made a similar observation and analyzed the historical evolution and convergence of three HR-related fields: human resource management (HRM), human resource development (HRD), and organization development (OD). A field left out in their analysis is HPT. Many learning professionals recognize HPT as a more comprehensive approach to improving organizational performance issues (Molenda & Pershing, 2008; Pershing, 2006). However, little research has been done to advance the theory development of HPT and discuss its relationships within HR fields. This study adds a new perspective to that of Ruona and Gibson's historical analysis of HR fields by examining convergence issues from a theory development perspective. (Contains 1 figure and 3 tables.)