A new fluorescent polystyrene derivative is reported in which a stilbene-based chromophoric pendant group is attached on average to each third monomeric unit. Poly[styrene-co-(p-(stilbenylmethoxy)styrene)] showed fluorescence emission from intra- and interchain interaction. The model compound p-((p-ethylphenoxy)methyl)stilbene is the first stilbene derivative to show aggregate emission in solution at room temperature reported to date. It is proposed that the emission originates from the association of chromophores in the ground state forming a fluorescent dimer or aggregate complex.