A major health care policy issue in this era of accountability is controlling the introduction and utilization of increasingly sophisticated and expensive health care technologies. Data are needed about both the effectiveness and the costs of assistive technologies before making decisions without relying on "that's what we did last time," "gut feelings," or even "educated guesses." Services, such as assistive technology, fall in the category where rigorous scientific evidence about cost-effectiveness is virtually nonexistent. The field of medical technology assessment has been studying cost-effectiveness for decades and offers many methodological ideas to related fields such as assistive technology. Based on the experiences of medical technology assessment, the measurement of health state preferences and its use to estimate quality-adjusted life years is discussed in this paper. Economic evaluation can be defined as the comparative analysis of alternative courses of action in terms of both costs and consequences. Information from economic evaluation studies, including the use of quality-adjusted life years as an outcome measure, helps us to determine which health care services we can afford to incorporate into routine clinical practice. The major forms of economic evaluation for health care described in this paper are cost-benefit, cost-effectiveness, and a special form of cost-effectiveness, cost-utility. Important national and state health care policies are being considered and implemented on the basis of economic evaluation data and these are bound to have major implications for assistive technology. The assistive technology field needs to be aware of these methods both to understand how large scale health-related policy decisions are impacted by economic evaluations and to become participants in and contributors to this process.