Many older people (over 80 years) are excluded from the use of new information and communication technology (ICT) because of the prevalence of mild to moderate memory problems in this group. This is a factor which contributes to the tendency for them to become socially isolated and mentally under-stimulated and inactive, a situation which may exacerbate dementia and associated cognitive impairment. To understand any group of users, the design team needs to get to know them. Spending time with members of this particular group, and especially observing and participating in their normal social activities, provides many unexpected insights on which to base design decisions. Older people with mild to moderate cognitive impairment often cannot learn new skills, or at least cannot retain them. However, longstanding knowledge generally remains. For this reason, a design based around an interaction metaphor from earlier technology can prove effective. We introduce the MAMA (Mobile Augmented Memory Aid) project, aimed at older users with mild to moderate cognitive impairment. We describe the hardware and software prototypes that have resulted so far. We go on to present five design principles developed during the project, and suggest that these may serve as a general approach to designing technology for older people. We indicate future work and how our approach can be applied more generally.