Reaction-induced crystallization during polymerization is an attractivemethod for the morphosynthesis of poorly processable rigid polymers, because it is not limited by the intractability of polymers. This method is applied to morphosynthesis of poly(ether imide)s by Takashi Sawai, Kanji Wakabayashi, Shinichi Yamazaki, Tetsuya Uchida, and Kunio Kimura on page 1293. The fibrillar crystals of poly[4-(1,4-phenylene)oxyphthalimide] are formed as the precipitates. Wide varieties of one-dimensional structures of poly[4-(1,4-phenylene)oxy phthalimide-co-4-phthalimide] are synthesized such as ribbons, cones, rods and fibers, depending on the copolymerization ratio. The morphology of the poly(ether imide)s can be controlled by not only the polymerization condition but also the aid of copolymerization.