The degree of clinical decision making and clinical productivity among nurse practitioners (NPs) is of great interest to policy makers and planners involved in providing appropriate outpatient primary care services. The authors performed a statewide mailed survey of all NPs practicing either full-time or part-time in Wisconsin (response rate of 72.1%) to address the following research questions: Do the demographic characteristics, practice attributes, and primary practice settings of NPs impact their level of clinical decision making (e.g., the autonomy to order laboratory and radiological tests or to refer a patient to a physician specialist other than their collaborating physician)? Do NPs' levels of clinical decision making correlate with their outpatient clinical productivity, adjusting for demographic characteristics, practice attributes, and primary practice settings? The multiple linear regression results indicated that having more years in practice as an NP, practicing in the family specialty area (vs. a combined other category, which included pediatrics, acute care, geriatrics, neonatal, and school), treating patients according to clinical guidelines, practicing in settings with a fewer number of physicians, and practicing in a multispecialty group practice versus a single-specialty group practice were associated with greater levels of clinical decision making. However, NPs who primarily practiced in a hospital/facility-based practice, as compared with a single-specialty group practice, had lower levels of clinical decision making. After adjusting for demographic characteristics, practice attributes, and primary practice settings, NPs with greater clinical decision-making authority had greater outpatient clinical productivity. The conclusions discuss the policy implications of the findings.