A user-centered design approach is crucial when designing successful products and technologies for older adults. However, this approach can have significant drawbacks in terms of the time and expense involved, as this process often involves having participants come into the lab for testing. Performance modeling can supplement – and in some cases replace – this process. The goals for this chapter are to show how modeling approaches originated and how they can be used to predict older adults’ movement time (Fitts’ Law) and to predict performance with different tasks (GOMS modeling for cellphones, driver dilemma zones), by using cases from CREATE research.