Corporations are implementing employee involvement programs in both union and nonunion settings in response to growing environmental pressures. This study examines the relationships among environmental pressures, corporate ideology, and participative practices in union and nonunion settings and tests two industrial relations models. Questionnaires measuring environmental pressures, corporate ideology, and participation were completed and returned by the Vice President of Human Resources (or similar corporate executive) in 159 of the largest manufacturing companies in the United States. Multiple regression results show that environmental pressures exert little effect on corporate ideology, but ideology has a significant effect on participative practices in both union and nonunion settings.