As older adults increasingly make use of the Internet, the study of web site usability for older adults is becoming increasingly relevant. Web site usability is concerned with both utilitarian (i.e. functional) and hedonic (i.e. pleasure-related) aspects. This study explores the impact of age on select utilitarian (mental model accuracy and performance) and hedonic (disorientation and engagement) measures of web site usability, and the subsequent impact of these utilitarian and hedonic measures on user satisfaction. An experiment was conducted with 50 younger and 47 older participants. The results suggest that age has a more pronounced impact on utilitarian constructs than hedonic ones. Specifically, older adults were less able to create an accurate mental model of the web site and in turn had poorer performance within the web site. In terms of impact on user satisfaction, the contribution of hedonic constructs was significant while the impact of utilitarian constructs was not.