We present experiences and insights into the participatory design of an orientation aid with individuals who have anterograde amnesia and therefore have extreme difficulty storing new memories. We discuss our design of the design process, and present a set of techniques used to support memory during and between design sessions. We generalize these ideas into an analytical framework for researchers and practitioners who intend to use participatory design with persons having various kinds of cognitive impairments. Through this process, we have conceived, designed, and developed the OrientingTool, a software application for Personal Digital Assistants that can be used by amnestics to orient themselves when feeling lost or disoriented. Two complementary studies were conducted to evaluate the effectiveness of this tool in ecologically valid contexts. Our preliminary findings suggest that it improves an amnestic's independence and confidence in handling anxious situations when disoriented.