The fungicides tebuconazole and chlorothalonil were successfully incorporated into polymeric nanoparticles with median particle diameters of 100-250 nm. Polyvinylpyridine (PVPy) and polyvinylpyridine-co-styrene (10% styrene and 30% styrene) were employed as the polymer matrix. The size of the nanoparticle increased with increased styrene content. The biocide also affected particle size, with chlorothalonil consistently yielding larger nanoparticles than tebuconazole. The release of the biocides from the polymeric nanoparticles was studied by suspending them in water. The release rate of both tebuconazole and chlorothalonil decreased with increased styrene content in the matrix, and chlorothalonil consistently released more slowly from the polymeric nanoparticles than did tebuconazole. It was found that biocides were successfully introduced into solid wood by incorporating them within polymeric nanoparticles, suspending the nanoparticles in water, and using the suspension to treat the wood with conventional pressure treatments. Once in the wood, the polymer matrix serves as a reservoir for the biocide and controls its release rate into the wood. Southern pine sapwood samples were treated with biocide-containing nanoparticles suspended in water, then exposed to the wood decay fungus Gloeophyllum trabeum using a simple wafer test. Samples exhibited fungal resistance at appropriate levels of biocide incorporation.