An acrylate-functional soybean oil-based macromonomer (SoyAA-1) was synthesized in high yields utilizing sequential amidation and acrylation processes to serve as an internal plasticizer in emulsion polymers. The structure and structure–property relationships of this unique macromonomer were validated with FTIR, NMR, and LC-MS. The viability of SoyAA-1 as a comonomer in emulsion polymerization was established via copolymerization with methyl methacrylate (MMA) at varying copolymer weight compositions. The effect of increasing SoyAA-1 levels and concomitantly higher allylic functionality was measured through film coalescence, minimum film forming temperature, and initial and progressively increasing glass transition temperature(s). The results indicate that synthetic modification of a renewable resource, soybean oil, can yield a valuable monomer that can be copolymerized in high yields via emulsion polymerization to produce practical and mechanically stable latexes for a variety of coatings applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40249.