Firms have since long given their regular customers special treatment. With the help of IT, many firms have established formal ways to do this. An example is a so-called customer rewards program (CRP), by which the firm rewards the customer for repeated purchase. Firms allocate large resources in these programs with millions of customers enrolled. Hence, it seems important that the CRP works effectively. By effective we mean that it increases sales. Whether it is effective or not is a matter of how it is designed. We study how many membership levels the firm should offer in an effective program. We also study if customers prefer individual or group rewards and whether a CRP can break and create habitual purchasing behavior. In the study, we also analyze under what conditions the customer prefers a CRP over a sales promotion. In general, the study adds to the understanding of Customer Rewards Programs as an incentive structure. There are many different ways to design these incentives and especially the continuing development of IT is expected to influence the future design and role of these types of programs.