The crystallization problem has been conquered by dynamic covalent chemistry in synthesis and reticular chemistry in materials design. This chapter reviews progress in the crystallization and structural linkages of Covalent organic frameworks (COFs). The selection of solvents and temperature to maximize the error correction associated with the boroxine ring–forming reactions can optimize the crystallinity of the boroxine-linked COFs. Boronic ester linkage–built up COFs have high crystallinity but low hydrolytic and chemical stability due to the reversibility of the reactions, which leads to their decomposition upon exposure to water or acid. The condensation of diols with trialkyl borate in the presence of basic catalysts has been explored for the synthesis of spiroborate-linked COFs in which the negatively charged boron ions are located on the edges with different cations as counters ions. Imine-based COFs constitute the largest amount of COFs based on Schiff base chemistry.