Are there differences in the patterns of use of health services and enrollment/disenrollment between previously-uninsured enrollees in state-sponsored insurance demonstrations and commercially-enrolled individuals in the same health systems? The objective of the study of demonstrations in Maine and Washington was to aid policymakers, insurers, and program planners in developing cost-effective programs for the uninsured. This study, conducted by the University of Southern Maine, compared health status, demographic characteristics, and health care use among demonstration and commercially enrolled populations. It also evaluated the effect of prior insurance status and plan cost sharing features on the use of health services and disenrollment.