The covalent casting of noncovalent architectures serves to define large covalent constructs that express well-defined modes of aggregation. In the case of one-dimensional hydrogen-bonding motifs, covalent casting yields molecular strands that adopt a duplex mode of aggregation. The effectiveness of this design principle is illustrated through the casting of the aminotriazine hydrogen-bonding motif. These studies have led to the conception of a new family of topographically defined oligomers, which, akin to DNA, self-assemble in the form of a duplex through the action of interstrand hydrogen bonds.