Introduction: A global shortage of doctors has led to strategies to improve access to care. The physician assistant/associate (PA) was established in North America and Africa in the 1960s in response to medical shortages. PA activity was cataloged to understand what determines their utilization in a country’s health system.Methods: A mixed-method study design began with searching the available literature regarding the development of PAs worldwide. Key words included “physician assistants”, “non-physicians”, “physician associates”, and “advanced practice providers”. Additional data was through an online search of reports; personal communications with researchers, policymakers, government officials, and practitioners in each country; visits by the authors to a number of the countries; and a review of official documents. In each country interviews included educators, policymakers and government officials who had direct involvement with the introduction of the PA concept, and clinically active PAs. Domain analyses were based on stratification of differences among countries: global region, income, physician to population ratio, attitudes of medical professionals, and practice/regulatory authority. Countries were segmented into two categories: well resourced and less well resourced.Results: The history and status of the PA concept into the health systems of 15 states were reviewed. The determinants for the successful incorporation of PAs include prevailing medical needs, a shortage of physicians or an aging physician workforce; support and sponsorship by physician organizations and government agencies; the ability to mobilize and establish a legal and regulatory framework to accommodate PAs; and evidence that their introduction is acceptable to patients, physicians, and other health professionals.Discussion: The introduction of PAs into health systems occurs because their education is less expensive and time intensive than physicians. In addition, graduates are more likely to occupy roles where there is scarcity of doctors such as in rural and underserved areas. In most instances, a physician-dependent role permits their introduction into health systems in a non-threatening manner to doctors and their practices. The utilization of PAs, particularly in primary healthcare roles, increases access to services, is cost-beneficial, and shows a physician-equivalent quality of care.Conclusion: The PA has been a remarkable health workforce policy development that has spread among countries’ health systems and is likely to continue.