Wildlife tourism attractions such as zoos are uniquely placed to make an impact on people’s everyday environmentally responsible behaviors. However, research suggests that visitors who leave such sites with a heightened awareness and good intentions rarely translate their intentions into post-visit environmental actions. This article reports on the development of a website-based action resource designed to reinforce, complement, and extend zoos’ on-site conservation messages and support visitors’ translation of environmental behavioral intentions into actions. The effectiveness of the website in encouraging post-visit engagement in environmental behavior was tested using an experimental design with a follow-up sample of 475 zoo visitors across four sites in three countries. The group that had accessed the website scored significantly higher on a behavior change index than the group that had not accessed the website. Website features identified as most effective in engaging visitors and maximizing their uptake of environmentally sustainable behavior are discussed.