The coassembly of two oligo-(p-phenylene vinylene) (OPV) derivatives with different sizes and opposite chirality is studied. Short R-chiral ROPV3 molecules experience a high energetic mismatch penalty when incorporated in helices formed by long S-chiral SOPV4 molecules. In contrast, SOPV4 easily coassembles into helices dominated by ROPV3. As a result, the coassembly behavior (i.e., mixing or phase separation of ROPV3 and SOPV4 within the assemblies) highly depends on the ratio between both molecular building blocks. By a combination of experiments and models, the assembly pathways are analyzed. Furthermore, the model allows identifying key parameters in the coassembly behavior, such as the cooperativity and the mismatch penalties. The model-driven approach is anticipated to be generally applicable in the engineering of functional supramolecular copolymers. This article is dedicated to the 70th birthday of Jean Frechet and we thank him for being a continuous source of inspiration for our group. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 385-391