One of the major challenges in current user interface research and development is the accommodation of diversity in users and contexts of use in order to improve the self-efficacy of citizens. A common banking service, which should be designed for diversity, is the Automated Teller Machine (ATM). This paper describes the various user-centered design techniques to involve the future users of an ATM for illiterate persons, and reports the results of applying the techniques to a group of six Dutch functional illiterate persons. First, it has resulted in a set of user requirements and promising redesign concepts for the current ATM, relating to hardware, functionality, order of actions, lay-out, interaction modalities, and the mental model of cash withdrawal. Second, it has provided insight into how user-centered design techniques should be applied to this specific, but heterogeneous, user group.