Hyperbranched polyesters are among the most common hyperbranched polymers. One of the interesting features of hyperbranched polyesters is that they contain unreacted hydroxyl and carboxylic acid groups at the linear and terminal structural units, which can be postmodified to adjust thermal, solubility, or mechanical properties, or to prepare core-shell type architectures. This article reports on the synthesis of a novel class of hyperbranched polyesters via an A(2) + B-3 type Baylis-Hillman polymerization of 2,6-pyridinedicarboxaldehyde and trimethylolpropane triacrylate. Baylis-Hillman polymerization generates highly functional polyesters that contain not only unreacted aldehyde and/or acrylate groups at the linear and terminal structural units but also chemically orthogonal vinyl and hydroxyl groups along the polymer backbone. Using 3-hydroxyquinuclidine as the catalyst, hyperbranched polymers with number-average molecular weights up to 7500 g/mol and degrees of branching up to 0.81 were obtained. To demonstrate the versatility of these hyperbranched polyesters to act as platforms for further derivatization, the orthogonal postpolymerization modification of the hydroxyl, vinyl, and pyridine functional moieties with phenyl isocyanate, methyl-3-mercaptopropionate, and methyl iodide is presented. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 25-34, 2012