Two opposing theories have been suggested to describe the relationships among member dissatisfaction with a prepaid group practice (PGP), the choice to go outside for care normally covered by the plan, and disenrollment from the PGP: 1) out-of-plan use--a consequence of dissatisfaction, precedes disenrollment and 2) dissatisfaction produces two independent effects--out-of-plan use and disenrollment. Preliminary results are reported on an evaluation of these relationships based on a sample of 1823 families at the Medical Care Group of St. Louis. Dissatisfaction is found to be the most important predictor of both out-of-plan use and disenrollment. However, no direct relationship exists between the latter two variables. This result lends support for the model, which specifies that PGP members respond differently to dissatisfaction with the plan; some go outside the PGP for their care while others simply disenroll.