IT investment by organizations in India has increased significantly over the last 10 years, as Indian firms have deployed IS for modernizing and reengineering their processes. This paper analyzes, in an exploratory vein, organizational and strategic imperatives that have influenced IS assimilation and evolution of the IS application portfolio in Indian firms. It first identifies three categories of organizations with respect to IS assimilation, and describes strategic and organizational factors characteristic of each group. Next, it traces the evolution of the IS application portfolio in each of the studied firms and analyses accompanying changes in strategic and organizational factors. The paper builds on IS assimilation studies in organizations from developed societies, and describes issues unique to IS assimilation in Indian firms. It is based on data collected from case studies of IS deployment in nine Indian organizations.