The purpose of this study was to discover how to efficiently use tailored messaging to increase recreational water users' behavioral intentions to perform specific behaviors that prevent the spread of Aquatic Invasive Species (AIS) and Viral Hemorrhagic Septicemia (VHS). The objectives were to identify the most effective message structure and message order for signs targeting seven behaviors that reduce the spread of AIS and VHS, and to examine the moderating effect of AIS and VHS knowledge and awareness on behavioral intentions. The population of this study consisted of students 31 years of age and younger attending Southern Illinois University Carbondale (μ = 21.06; n = 680). The study design tested messages according to the Optimal Arousal Theory. The respondents completed an 11-item questionnaire that measured knowledge, awareness, and behavioral intentions, and included one of 34 sign treatments. When asked how knowledgeable respondents were about AIS and VHS, 48% of respondents indicated that they were not knowledgeable. Respondents were also asked the extent to which they believed AIS is a problem in Illinois; 43% reported AIS to be a "moderate" problem. Seven (7) items on the questionnaire measured intention to perform specific behaviors that may reduce the spread of AIS and fish disease between water bodies. Knowledge and awareness (only when interacting with knowledge) were found to be covariates of behavioral intentions. Complex results were revealed regarding the most effective tailored message, as no one sign significantly increased all seven behavioral intentions and the number of treatments significantly increasing behavioral intentions varied by behavior (i.e., 11 treatments had a significant influence on the behavioral intention for "visual inspections;" 4 treatments had a significant influence on the behavioral intention for "drain water;" 8 treatments had a significant influence on the behavioral intention for "avoid bait release;" 6 treatments had a significant influence on the behavioral intention for "remove plants and animals;" 4 treatments had a significant influence on the behavioral intention for "flush motor;" and, 11 treatments had a significant influence on the behavioral intention for "rinse boat". Results suggest mainly positively phrased messages works best when trying to stimulate environmentally responsible behavior (ERB). The recommendations from this study encourage strategic use of communication to enhance natural resource management as this study yielded gains in predicted behaviors of respondents to reduce the spread of AIS and VHS. The study also demonstrates the need to increase recreational water users' AIS and VHS knowledge improve the likelihood that they will perform desired behaviors.