Data on the ways in which alternative forms of managed care affect the costs, quality, and outcomes of mental health are needed to inform health policy and clinical care decisions. Such evaluations, however, are difficult to implement for conceptual and practical reasons. The definition of managed mental health care is reviewed, alternative forms are described, and the activities and procedures that constitute managed care are identified. Examples from existing studies are used to describe the common roadblocks to implementing evaluations and to suggest methods for dealing with these barriers.