Health maintenance organizations (HMOs) are undergoing major changes, among them the following: Enrollee growth will continue to be strong, although the rate of growth will diminish. HMOs will develop new product lines, such as offering preferred provider organizations and various cost management services. The competitive environment has become tougher. Quality of care concerns among the public are on the rise. Employers, while generally supportive of HMOs, are also questioning and changing their contractual relationships with them.