SYNOPSISThe article deals with data treatment problems associated with the estimation (via dualdetection size exclusion chromatography) of the independent distributions of molecular weight and functionality in a derivatized hydroxyl-terminated polybutadiene. Calculations are based on an approach originally developed for linear copolymers and include corrections for ( a ) effect of functional groups on instantaneous mass and molecular weights, ( b ) dependence of refractive index with molecular weight, and (c ) instrumental broadening. Compared to other more laborious analytical methods, the proposed technique is simple and provides accurate results.