BACKGROUND CONTEXT: Defining success after spinal surgery remains problematic. The minimal clinically important difference (MCID) in pain or functional outcomes is a common metric often calculated independent of perceived risk and morbidity, which is an important consideration in large procedures such as spinal fusion and instrumentation. PURPOSE: The purpose of this study was to describe a method of assessing treatment success based on prospective, patient-reported "minimum acceptable" outcome for which they would undergo a procedure. These goals can then be compared at follow-up to gauge how frequently patient goals are met and determine correlation with patient satisfaction. STUDY DESIGN: This is a clinical descriptive study of the patient-reported minimum acceptable outcomes for spinal fusion surgery. OUTCOME MEASURES: Minimum acceptable outcomes were determined by patients on preoperatively administered standard questionnaires regarding ultimate pain intensity, functional outcome (Oswestry Disability Index [ODI]), medication usage, and work status. Satisfaction with outcomes was assessed at 2-year follow-up. METHODS: One hundred sixty-five consecutive patients undergoing lumbar fusion for either isthmic spondylolisthesis or disc degeneration were asked to preoperatively define on standard questionnaires their minimum acceptable outcomes after surgery. Two-year outcomes and satisfaction were subsequently reported and compared with the preoperatively determined minimum acceptable outcomes. RESULTS: Both the spondylolisthesis and the degenerative disc disease (DDD) groups reported that a high degree of improvement was the minimum acceptable threshold for considering spinal fusion. A large majority indicated that the minimum acceptable outcomes included at least a decrease in pain intensity to 3/10 or less, an improvement in ODI of 20 or more, discontinuing opioid medications, and return to some occupational activity. Achieving the minimum acceptable outcome was strongly associated with satisfaction at 2 years after surgery. Patients with compensation claims, psychological distress, and other psychosocial stressors were more likely to report satisfaction in the absence of achieving their minimum acceptable outcome. CONCLUSIONS: Patients with spondylolisthesis and DDD both have relatively high minimum acceptable outcomes for spinal fusion. In these cohorts, few subjects considered more commonly proposed MCIDs for pain and function as an acceptable outcome and report that they would not have surgery if they did not expect to achieve more than those marginal improvements. Although there was good concordance between achieving the minimum acceptable outcomes and ultimate satisfaction, patients with significant psychosocial factors (compensation claims, psychological distress, and others) are less likely to associate satisfaction with outcomes with actually achieving these improvements.