The general model proposed, which assumes that crack growth plays an important part in the abrasion process when abrasion patterns are produced, is supported by evidence from the behavior of noncrystallizing rubbers. In particular, the rate of movement of the pattern across the surface is closely related to the crack growth behavior. Natural rubber behaves under abrasion conditions as if it were prevented from exhibiting its usual crystallization-enhanced strength. An important factor determining the abrasion rate, in addition to the crack growth behavior, is the angle at which the hypothetical cracks at the pattern base grow. What determines this angle is not yet clear, but it appears to be closely related to the geometry of the pattern, and it seems likely, from a study of this geometry, that much of the loss of rubber occurs from the steeply raked face of the pattern. The pattern spacing, as well as depending on the abrading force, also appears to be influenced by the test temperature and the glass transition temperature of the rubber, suggesting that viscoelastic considerations are important.