With a span as long as the history of polymer science itself, post-polymerization modification represents a versatile platform for the preparation of diversely functionalized polymers from a single precursor. Starting with the initial efforts by Staudinger in the 1920s, many of the early developments in modern polymer science can be attributed to the utilization of post-polymerization modification reactions. The scope of post-polymerization modification has greatly expanded since the 1990s due to the development of functional group tolerant controlled/living polymerization techniques combined with the (re)discovery of highly efficient coupling chemistries that allow quantitative, chemoselective, and orthogonal functionalization of reactive polymer precursors. After some basic mechanistic considerations, this Highlight will provide an overview of the development and evolution of eight main classes of post-polymerization modification reactions. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013