Confronted with the coronavirus disease 2019 (COVID-19) pandemic, New York City Health + Hospitals, the city's public health care system, rapidly expanded capacity across its eleven acute care hospitals and three new field hospitals. To meet the unprecedented demand for patient care, NYC Health + Hospitals redeployed staff to the areas of greatest need and redesigned recruiting, onboarding, and training processes. The hospital system engaged private staffing agencies, partnered with the Department of Defense, and recruited volunteers throughout the country. A centralized onboarding team created a single-source portal for medical care providers requiring credentialing and established new staff positions to increase efficiency. Using new educational tools focused on COVID-19 content, the hospital system trained twenty thousand staff members, including nearly nine thousand nurses, within a two-month period. Creation of multidisciplinary teams, frequent enterprisewide communication, willingness to shift direction in response to changing needs, and innovative use of technology were the key factors that enabled the hospital system to meet its goals.