The present study integrates institutional factors and employee-based collective processes as predictors of 2 key implementation outcomes: implementation effectiveness and innovation effectiveness (Klein, Conn, & Sorra, 2001). Specifically, the authors proposed that institutional factors shape employees' collective implementation efficacy and innovation acceptance. The authors further hypothesized that these employee-based collective processes mediate the effects of institutional factors on implementation outcomes. This integrative framework was examined in the context of 47 agencies and ministries of the Korean Government that were implementing a process innovation called E-Government. Three-wave longitudinal data were collected from 60 external experts and 1,732 government employees. The results reveal the importance of management support for collective implementation efficacy, which affected employees' collective acceptance of the innovation. As hypothesized, these collective employee dynamics mediated the effects of institutional enablers on successful implementation as well as the amount of long-term benefit that accrued to the agencies and ministries. (PsycINFO Database Record (c) 2009 APA, all rights reserved).