We undertook a multiyear evaluation of the NaturePalooza Science Festival, an annual public event designed to increase science literacy and sustainability behavior, to measure impacts. Surveys conducted at the 2014 and 2015 events and 6 months after the 2015 event showed that 77%, 92%, and 100% of respondents, respectively, learned new information. In 2014 and 2015, 85% and 68% of respondents, respectively, intended to change at least one behavior. Additionally, in the 2015 on-site and follow-up surveys, 66% and 62% of respondents, respectively, reported implementing sustainability behaviors. These findings demonstrate that such events can have a positive, measurable impact on visitors' science literacy and sustainability behaviors.