Consumer lending is the sleeping giant of the financial sector. The growth in consumer credit over the last 50 years is truly spectacular. The marketplace for total retail banking and consumer lending is enormous; it exceeds corporate debt by more than 50% in many countries. It was only with the US sub-prime mortgage crisis of 2007 and the consequent worldwide credit crunch that consumers, lenders, and banking regulators really woke up to its importance. Yet the literature on consumer lending and consumer credit modelling is minimal compared with that on corporate lending or the exotic equity-based derivatives. Part of this is because credit scoring, the risk assessment approach introduced in the 1950s, has worked so well since then that there has been little reason to analyse it deeply. Its success has been down to the fact that it focused on one objective—to assess the default risk of prospective and existing borrowers in the next year—and one decision—whether to accept an applicant for a loan. The extension from acceptance scoring to behavioural scoring allowed other decisions on whether to extend further credit or whether to try and cross-sell another product to the borrower but as we have shown this can be reinterpreted as another form of the acceptance decision.