Arenediazonium chemistry has been explored under a wide variety of experimental conditions but relatively little attention has been given to their reactions in micellar and macromolecular systems. During the last years, several groups have investigated the effects of micellar and macromolecular systems on dediazoniations. Investigations point towards two main directions; for one side the basic physical organic aspects of the reactions have been explored. Alternatively, new methods to estimate interfacial compositions of weak nucleophiles in colloidal interfaces have been developed based on the atypical and unique characteristics of dediazoniation chemistry. The present review is aimed to summarize recent developments on arenediazonium chemistry in the presence of micellar and macromolecular systems. As we will see, micellar systems mainly change dediazoniation product distribution but do not modify significantly dediazoniation rate constants, in contrast with crown ethers, which alter significantly the rate constants but not the product distribution. Cycodextrins may change both rate constants and product distribution, depending on the nature of the arenediazonium.