This paper discusses the empirical and theoretical underpinnings of the travel cost method (TCM) for estimating nonmarket benefits at an outdoor recreation site. The conventional TCM model is simple to use and provides results that are easy to interpret. However, it does not describe the actual behavior of recreationists as they purchase goods and services for the purpose of making trips to an outdoor recreation site. There is an alternative model that is more congruent with the empirical behavior of recreationists. This model is called the multi-commodity or total expenses TCM model. The total expenses model can also be used to estimate the nonmarket benefits provided by trips to an outdoor recreation site. Moreover, the total expenses model can be derived from the conventional basic postulates of utility maximization. Our purpose in delineating the total expenses model is not to replace the conventional model, but to provide an alternative model. We apply this model to survey data gathered from Trinity River recreationists, and estimate annual nonmarket benefits conferred from recreation activities of US$406 million. 1998 Published by Elsevier Science Ltd.