The Paycheck Protection Program (PPP), a principal element of the fiscal stimulus enacted by Congress during the COVID-19 pandemic, aimed to assist small businesses to maintain employment and wages during the crisis. The authors use high-frequency administrative payroll data from ADP—one of the world’s largest payroll processing firms—to estimate the causal effect of the PPP on the evolution of employment at PPP-eligible firms relative to PPP-ineligible firms, where eligibility is determined by industry-specific firm-size cutoffs. It is estimated that the PPP boosted employment at eligible firms by between 2 percent to 5 percent at its peak in mid-2020, with this effect waning to 0 to 3 percent throughout the remainder of the year. Employers retained an estimated additional 3.6 million jobs due to the PPP as of mid-May 2020, and 1.4 million jobs at the end of 2020. The implied cost per year of employment retained was $169,000 to $258,000, equal to 3.4 to 5.2 times median earnings.