Compatibility studies were performed on four experimental toxicants to determine their applicability for incorporation into five commercially available water borne resins for possible use by the U. S. Navy as marine antifoulant coatings. The following parameters were examined as a function of toxicant loading: wet grind, drying time, film hardness, and enamel holdout (a measure of film integrity). A sample of each resin/toxicant system was prepared and used to coat fiberglass panels for evaluation by immersion testing by the U. S. Navy.