This review (sourced from +/- 300 references) is focused on the use of soft ionization mass spectroscopy to characterize the products of polymerization/degradation reactions thereby yielding mechanistic information. We provide a brief description of the different spectrometers techniques available for polymer analyses, including MALDI-TOF, ESI-MS, and a precis of mass spectrometer performance, together with a brief critique summarizing the limitations and advantages of each. On MALDI-TOF, we detail the possible side reactions that can occur when the MALDI-TOF technique is employed to analyze polymers, and emphasize the importance of correct sample preparation. ESI-MS is also given attention and emphasis is placed on the limitations and optimization of samples for successful analyses. This review is presented in the context of polymer science research, with special attention focused on the use of MS data to gain insights into mechanistic processes. (c) 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013, 51, 1475-1505