Cross-sell models are used to predict the probability or value of a current customer buying a different product or service from the same company. Selling to current customers is one of the easiest way to increase profits and allows companies to carefully manage offers to avoid over-soliciting and possibly alienating their customers. In this study, by using the real database of an insurance company in Korea, we try to explain the steps of actual data mining process. Especially, this study aims to develop cross-sell models to predict the probability which a current customer of automobile insurance buys long-term insurance product.