Interpretive signage found in American zoological parks play an important role in the ongoing process for visitor persuasion. While aiming to prevent different populations of endangered species from becoming extinct in the wild, zoos are facing a myriad of new challenges posed all over the natural world. This study investigates how media contained in the zoo setting address global problems caused by humans and why such media is used to respond against anti-zoo criticisms. The study originates from research conducted from June to August 2011 and include visitation to the following animal parks: Oregon Zoo, Portland, Oregon; Sacramento Zoo, Sacramento, California; San Diego Zoo, San Diego, California; and Smithsonian's National Zoo, Washington, D.C. The subsequent analysis revealed the primary topics for public discourse: Education, Ecosystems, Consumer Behavior/Awareness, Cultural and Customary Traditions, Zoo's Direct Involvement Concerning Environmental or Species Issues, Research Orientation, and Promotion of Visitor Involvement Concerning Environmental Issues.