It is a trend among museums to not only encourage understanding or appreciation of exhibit content but also encourage behavioral change among visitors after their exhibit experience. Exhibits focusing on wildlife and habitat conservation, nutrition and health, advocacy, and family learning/literacy all hinge on making a change in the visitors' behavior after they leave the museum. Yet there is surprisingly little research about how often museum exhibits, much less museum Web sites, actually lead to changes in visitor behavior. To promote further discussion and research in the field, we review some of the challenges and promising examples in the museum field. We also review some of the considerations that went into the development of Conservation Central, selected Best Museum Web site at Museums and the Web 2004, which we developed for Smithsonian's National Zoo. We conclude by proposing a set of Web site guidelines that include goals for encouraging behavioral change among visitors.