A national survey showed that nearly half of all major managed care organizations in the United States refuse to credential nurse practitioners as primary care providers. In nurse-managed health centers throughout the country, nurse practitioners provide primary care to underserved populations with similar outcomes to primary care physicians. Insurers' prohibitive credentialing and reimbursement policies reduce these centers' capacity for growth and, in turn, threaten the long-term sustainability of a key component of the health care safety net. Two years after conducting a national survey of insurers' credentialing and reimbursement policies regarding primary care nurse practitioners, researchers returned to the subject matter and found that many of the same financial barriers to nurse-managed health center sustainability still exist. Although some progress had been made since 2005, this progress did not appear to be attributable to regulatory changes or renewed enforcement of existing laws.