Boron trifluoride catalyzed epsilon-caprolactone polymerization in the presence of glycerol can produce poly(epsilon-caprolactone) with a high weight-average molecular weight and a broad molecular weight distribution. This article reports an investigation of the polymerization mechanism to determine the formation of these molecular weight features through a study of the polymerization kinetics and the molecular structure with NMR. The polymerization proceeds via an activated monomer mechanism, resulting in polymer molecules with hydroxyl chain ends. The broad molecular weight distribution can be attributed to the etherification reactions between hydroxyl chain ends. (c) 2006 Wiley Periodicals, Inc.