Initially developed to overcome the limited low-temperature impact resistance of polypropylene (PP) and allow its application in subzero temperatures, the PP/elastomer blends became a very important and industrially relevant material class. Within the last 40 years, a whole range of PP impact copolymers from multireactor processes have been developed that are capable of covering wide application areas. This review summarizes their developmental history and presents options for the in-reactor design of these polymers and their modification by compounding with elastomers and fillers or reinforcements after the polymerization. An overview of the application range is also presented together with a glimpse into the future of this material class. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3028-3037, 2013