The paper demonstrates the potentiality of the self-seeding technique [3] for the growing of single crystals of polyethylene. It is shown that with appropriate measures, uniform single-layer crystals of strictly controlled habit can be obtained. Concrete recipes are given for the growing technique. The habit features are systematized as functions of crystallization temperature and concentration. Novel twin formations with coincident centers arising from this work are described and analyzed. Their origin is correlated with the result suggested by an associated investigation that the nuclei have a multicomponent structure [4]. The advantages of the new crystal-growing technique for other lines of work are pointed out.