AbstractApproximations in the Avrami treatment of impingement which arise when the growing crystalline bodies are rods or disks are discussed, with particular reference to the single‐crystal model. This model, previously fitted to the isolated primary crystallization of polymethylene, is extended to discuss the growth of the composite lamellar structures, axialites, and spherulites, and is here fitted to the crystallization of poly(ethylene oxide) and polystyrene. Both polymers are found to yield anomalous values of the Avrami exponent when analyzed in terms of the conventional Avrami equation. The new analysis reveals similarities in the behavior of all three polymers. The residual deviations remaining after the fit of the model to polymethylene and poly(ethylene oxide) follow the same pattern, and the temperature dependence of the rate constants associated with the model is similar for all three polymer