Objective: This study examined diversity during the late 1980s in managed care programs for mental health, alcohol abuse, and drug abuse to identify ways in which research can generate more meaningful data on the effectiveness of utilization review programs. Methods: Telephone interviews were conducted with representatives of utilization review programs for employee health insurance plans in 31 firms that employed 2.1 million people in 1990. Questions addressed qualifications of personnel, clinical criteria to authorize care, integration with employee assistance plans, penalties for not complying with utiization review procedures, outpatient review, and carve out of mental health and substance abuse review. Results: Large variations in utilization review programs were found. Programs employed a range of review personnel and used a variety of clinical criteria to authorize care. More than two-thirds did not carve out mental health and substance abuse review from medical-surgical review. Some firms' employee assistance plans were integrated with utilization review programs, while others remained unintegrated. Penalties for not following program procedures varied widely, as did review of outpatient services. Conclusions: Because of trends toward even more diversity in utilization review programs in the 1990s, research that identifies the specific features of managed care programs that hold most promise for controlling costs while maintaining quality of care will increasingly be needed.