A theory of infall of material into clusters of galaxies is developed and applied to the Coma chister. It is suggested that the infall phenomenon is responsible for the growth of cluster galaxies. The generation of a hot intracluster medium is discussed and its relation to the observed absence of normal spirals in rich clusters investigated. The inference made earlier by Gott and Gunn that the observed X-ray luminosity of Coma puts severe constraints on the deceleration parameter qo is further elucidated. We discuss the relation of these phenomena to the morphology of clusters, and find that some observed regularities in their observed properties can be explained.