A method for making a polymer or oligomer comprising the steps of making a first monomer comprising a substituted aromatic or heteroaromatic group by providing an aromatic or heteroaromatic group substituted with first and second director groups, performing metalisation at a first position on the aromatic or heteroaromatic group, performing electrophilic substitution so as to provide a first substituent group at the first position, and contacting in a reaction mixture the first monomer with at least two further monomers that independently are the same or different from the first monomer under conditions so as to form a polymer or oligomer, wherein the nature and positions of the first and second director groups regioselect the first position.