The fluorescence anisotropy decay method is used to measure the rotational diffusion of 9,10-diphenylanthracene and the segmental motion of anthracene-labelled polystyrene in tetrahydrofuran solutions of polystyrene. The concentration dependences of these two measures of microscopic friction are reported from pure solvent to 70% polymer at 4.5, 25.0 and 45.5-degrees-C. These results are compared to previously reported measurements of the translational diffusion of methyl red in the same system, and to the temperature dependence of the solution viscosity of a closely related system. The three measures of microscopic friction show similar concentration dependences.