We study bank responses to the Paycheck Protection Program (PPP) and its effects on lender balance sheets and profitability. To address the endogeneity between bank decisions and balance sheet effects, we develop a Bayesian joint model that examines the decision to participate, the intensity of participation, and ultimate balance sheet outcomes. Overall, lenders were driven by risk-aversion and funding capacity rather than profitability in their decision to participate and the intensity of their participation. Indeed, with greater participation intensity, banks experienced sizable growth in their loan portfolios but a decline in their interest margins. In counterfactual exercises, we show that the PPP offset a large potential contraction in business lending, and that bank margins would have fallen even more precipitously if lenders had not participated in the program. Although the PPP was intended as a credit support program for small firms, the program indirectly supported the margins of banks that channeled these loans.