Abstract: This invention relates to a nonleachable waterborne wood preservative composition that combines one or more resin acids, mostly or fully in the carboxylate anion form, with one or more organic biocides to enhance the efficacy of relatively high-cost organic biocides. Resin acids are cost effective and environmentally safe, and therefore can be used as a low-cost and environmentally-benign additive to help protect wood against wood-destroying fungi. Furthermore, wood treated with a waterborne resin acid formulation will have enhanced water repellency, which will result in better dimensional stability for wood exposed to water. This invention also provides a method for the use of the described composition.