Advanced practice registered nurses (APRNs) are nurses with advanced degrees who practice as certified nurse practitioners, certified nurse midwives, certified registered nurse anesthetists, or certified clinical nurse specialists. APRNs in these roles are often primary care providers and can provide acute, gynecological, and pain management care. In each state, scope of practice (SOP) laws determine which procedures and treatments APRNs may administer. In Missouri, APRNs are required to enter into collaborative practice arrangements (CPAs) with a physician to prescribe, administer, and dispense medications; examine and evaluate patients; and formulate treatment plans. In addition to defining APRN scopes of practice, Missouri statute (MO Rev. Stat. § 334.037, 104) restricts the number of APRNs that may enter into a CPA with a physician, defines geographic proximity requirements, and requires that physicians regularly review the services provided by APRNs.