A novel soybean oil-based vinyl-containing waterborne polyurethane (VPU) dispersion has been successfully synthesized from toluene 2,4-diisocyanate, dimethylol propionic acid and a 90 : 10 mixture of chlorinated soybean oil-based polyol and acrylated epoxidized soybean oil (AESO). Then, a series of VPU/acrylic grafted latices have been prepared by emulsion graft copolymerization of acrylic monomers (40 wt % butyl acrylate and 60 wt % methyl methacrylate) in the presence of the VPU dispersion, using potassium persulfate as an initiator. The structure, morphology, and thermal and mechanical properties of the resulting latices, containing 15-60 wt % soybean oil-based polyols as a renewable resource, have been investigated by Fourier transform infrared spectroscopy, solid state C-13 NMR spectroscopy, transmission electron microscopy, thermogravimetric analysis, dynamic mechanical analysis, and mechanical testing. The results indicate that graft copolymerization of the acrylic monomers onto the VPU network occurs during emulsion polymerization, leading to a significant increase in the thermal stability and mechanical properties of the resulting miscible grafted latices. This work provides new environmentally-friendly latices from a renewable resource with high performance for coating applications. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 3305-3314, 2011