One of the best summaries of the theory of friction between solid materials up to 1949 was published by Bowden and Tabor. However, little attention was devoted in this review to either theoretical or experimental results on the friction between rubberlike materials and other solids. In recent years, the literature on various aspects of the friction of rubberlike materials has become quite voluminous and unfortunately sometimes contradictory in the results and interpretations presented. This is understandable, to some extent, in the light of the fact that each individual research effort has usually been directed toward some particular aspect of the problem; certain, sometimes rather arbitrary, conditions are employed or assumed, and the results obtained are often rather unclear functions of these experimental or theoretical parameters. The situation is further complicated by the facts that at the very best, experimental frictional studies do not yield very accurate or readily reproducible data and the theories proposed, in many cases, are not subject to exact experimental verification. No comprehensive effort has been made, to date, to unify the various theories and to reconcile the conflicting experimental results on the friction of rubberlike materials and it is not the principal objective of the present review to do so. One of the aims is rather to report and summarize these sometimes divergent views in the hope that investigators in this field will be encouraged to study those areas in which knowledge is either inconclusive, contradictory or incomplete. Generally speaking, dynamic friction can be defined as the tangential reaction between two solids in relative motion in the presence of a normal force between the two solids. This definition can include both sliding and rolling friction. This review will be concerned principally with the sliding friction phase since rolling friction is generally conceded to be explained almost entirely by the internal friction of the deformable material. It has been stated, for example, that the rolling resistance of pneumatic tires at 80–95 mph is composed of 90–95% internal hysteresis, 2–10% surface friction and 1.5–3.5% air friction.