Older adults in the US are the fastest-growing demographic, and also the largest-growing group of internet users. The aim of this research was to evaluate websites designed for older adults in terms of (i) how well they adhere to ‘senior-friendly’ guidelines and (ii) overall ease of use and satisfaction. In Experiment I, 40 websites designed for older adults were heuristically evaluated based on their adherence to usability guidelines derived by the National Institute on Aging and the National Library of Medicine. In Experiment II, three websites with varying levels of guideline compliance were evaluated by older adults in a usability test. Results from this study indicate that the website most compliant with the ‘senior-friendly’ guidelines resulted in higher task success, but did not result in significantly better efficiency, satisfaction, or preference. These findings demonstrate the importance of using both guidelines and usability testing when designing websites for older adults.