This paper assesses the impact on consumption and debt repayment from a credit card promotional campaign offering cash-back rewards. Using account-level administrative data from a large U.S. financial institution, we employ a generalized difference-in-differences design and find that even with a small 1% cash-back incentive, the rewards program leads to a substantial change in consumer behavior. Cardholders joining the rewards program increase their credit card spending by 32% and their debt by 8%, with such behavior persisting in the long run. Evidence from credit bureau confirms that the higher spending and debt are not driven by cross-card substitution or similar promotions by other card issuers. Different consumer segments respond differentially to the promotional campaign. Consumers with a higher level of liquidity constraints and who are less financially literate demonstrate more pronounced responses.