We develop a model of a competitive market for non-linear credit contracts, and analyze the contract choices, loan-repayment behavior, and welfare of sophisticated and non-sophisticated borrowers with a taste for immediate gratification. Consistent with many credit cards and subprime mortgages, the baseline repayment terms of a competitive-equilibrium contract are cheap, but they are also inefficiently front-loaded and delays require paying large penalties.Non-sophisticated borrowers tend to borrow too much despite credit being for future consumption, and then to both pay the penalties and repay in an ex-ante suboptimal back-loaded way, leading to welfare losses that are typically large. Prohibiting large penalties for deferring small amounts of repayment-akin to some recent new regulations in the US credit-card and mortgage markets-can raise welfare.Keywords: hyperbolic discounting, sophistication, partial naivete, screening, consumer protection, subprime markets, credit cards Researchers as well as policymakers have expressed concerns that some contract features in the credit-card and subprime mortgage markets may induce consumers to borrow too much and to make suboptimal contract and repayment choices. 1 These concerns are motivated in part by