The copolymerization behaviour of 2-methylene-1,3-dioxepane (MDO) with styrene has been studied via pulsed-laser polymerization. The average propagation rate coefficients, [k(p)], were determined for a number of feed ratios of MDO ranging from 0 to 0.938 at both 30 and 40 degrees C. Both the [k(p)] and the polymer composition data indicate a complete absence of copolymerization - contrary to a previously published study. The experimental data indicate the homopolymerization of styrene, with the MDO merely acting as a diluent.