6,7-Bis(alkyloxy)-2,3-dihydrophthalazine-1,4-diones self-assemble into lactim-lactam trimeric disks in solution as demonstrated by SEC and NMR. With suitable substituents, as in Phthal8, Phthal12, and Phthal16, these disks self-organize into a thermotropic, columnar, discotic phase. The disubstituted phthalhydrazide unit thus represents a general motif for the recognition-induced generation of supramolecular, discotic liquid crystals by self-assembly.