The solvent and temperature dependent aggregation of high molecular weight bis[S-(+)-3,7-dimethyloctyl)] substituted poly(p-phenyleneethynylene) (PPE, 2) was examined by absorption, emission and circular dichroism spectroscopy. All herein employed methods strongly support the view that 2 forms ordered aggregates in the solid state and in solvent mixtures. This is the first case in which a chiral high molecular weight PPE displays its aggregation by both optical and chiroptical methods.