In the building community, there is a growing demand for high-performance, low-maintenance, and low-cost building products. To meet this demand, natural fiber-thermoplastic composites are being used to produce such products as decking, window and door elements, panels, roofing, and siding. In spite of the rapid growth in the use of these composites, little is known about their fastener performance. In this study, experimental fastener tests were performed on wood flour-thermoplastic composite panels. Results are presented for screw withdrawal, nail withdrawal, nail head pull-through, and lateral nail resistance tests. These results indicate that screw withdrawal, nail withdrawal, and nail head pull-through capacity are relatively unaffected by wood flour content. However, wood flour content affected lateral nail resistance. The use of pilot holes (predrilling) was found to have little effect on fastener capacity. The screw withdrawal capacity ofthe tested wood flour-thermoplastic composite panels was found to be equal to or greater than that of conventional wood panel products.