Polymer supported chemical reactions may include those using supported substrates, reagents and catalysts, and this Review Report describes all three types. In all cases the most frequent reason for the use of a polymeric support will be the ease of separation of the supported and the low molecular weight species. A further advantage which is becoming increasingly important is the safer handling of odorous or toxic substances, which can also reduce problems of toxic waste materials. In this state-of-the-art review the effects of polymer supports on reactions are explained, and a number of polymer supported reactions are described in detail, with the greatest emphasis on the area which is currently most attractive, that of polymer supported catalysts. Further details of many reactions can be obtained from the accompanying 408 references and abstracts from the Polymer Library, which provide an overview of work in this field since 1980.