Triclosan (TCS) is among the top 10 most persistent contaminants found in U.S. rivers, streams, lakes, and aquifers. Although TCS has not been found to be hazardous to humans, it can be toxic to aquatic environments and animals. The effects of TCS on growth rates and the locomotive behavior of the freshwater snail, Physa acuta, were studied by exposing snails to a range of environmentally-relevant trace concentrations previously documented in freshwater ecosystems. Effects of TCS on snail growth were calculated using a non-linear regression model, and effects on behavior were determined using a two-way analysis of variance. Environmentally relevant concentrations of TCS (0.5 to 1.0 μg/L) enhanced Physa growth rates at low concentrations, but slowed growth rates at concentrations greater than 5 μg/L. Acute exposure did not affect immediate snail behavior; however, chronically exposed snails moved more slowly than naïve snails. These data indicate that concentrations of TCS currently found in freshwater ecosystems can potentially affect the growth and behavior of snails.