AbstractIt has been confirmed by means of electron diffraction that lath‐shaped crystals of polyethylene are {110} reflection twins in which the chain molecules adopt a regularly folded conformation. The orientation and habit of the spiral terraces (or steps) which grow on the {001} faces of these crystals through the agency of screw dislocations is governed by the disposition and hand of the dislocations which, in some cases, can lead to the formation of lath‐shaped, twinned‐crystal terraces as well as “epitaxial {110} reflection twins.” The formation of the latter is taken as evidence that it is lateral accretion on a growing polyethylene crystal step which determines its habit and orientation rather than the epitaxial orientational influence of an underlying crystal terrace.It is shown that twinning forms an essential feature of growth of some of the more complex solution‐grown crystals of polyethylene which possess a radially symmetrical structure, in which the chain molecules are normal to the “radial” direction. In contrast with melt‐grown polyethylene spherulites, however, the b crystallographic axis in such crystals has a preferred tangential orientation. A brief indication is given of the influence of crystallization conditions on the preferred growth direction in the twinned terraces of such radiating crystals.