Five narrowly distributed fractions of phenolphthalein poly(ether sulfone) (PES-C) were studied in CHCl3 by both static and dynamic laser light scattering (LLS) at 25 degrees C. The dynamic LLS showed that the PES-C samples contain some large polymer clusters as in previously studied phenolphthalein poly(ether ketone)(PEK-C). These large clusters can be removed by a 0.1-mu m filter. Our results showed that [R(g)(2)](1/2)(z) = (3.35 +/- 0.13) x 10(-2) M(w)((0.52 +/- 0.03)) and [D] = (2.26 +/- 0.02) x 10(-4)M(w)-((0.54) +/- 0.03)) with [R(g)(2)](1/2)(z), M(w) and [D] being the z-average radius of gyration, the weight-average molecular weight, and the z-average translational diffusion coefficient, respectively. A combination of static and dynamic LLS results enabled us to determine D = (2.45 +/- 0.04) x 10(-4)M-((0.55 +/- 0.05)), where D and M correspond to monodisperse species. Using this scaling relationship, we have successfully converted the translational diffusion coefficient distribution into the molecular weight distribution for each of the five PES-C fractional The weight-average molecular weights obtained from dynamic light scattering have a good agreement with that obtained from static laser light-scattering measurements.