Rotational correlation times τ c for rubrene and tetracene are reported near and below T g in three polymers: polyisobutylene, polystyrene, and Bisphenol A polysulfone. A photobleaching method was used to obtain τ c values from 10 -1 to 10 3 s. In each polymer matrix, the orientation autocorrelation function for tetracene (the smaller probe) decays more rapidly and less exponentially than the correlation function for rubrene. τ c for a given probe at the T g of the matrices varies more than 3 decades. For the three polymers studied, probe rotation times at T g showed a systematic decrease with increasing matrix T g . Viscoelastic relaxation times characteristic of the Rouse modes of the matrix polymers are closely related to probe rotation times and also not constant at T g . Thus T g is not an isolocal mobility state for molecular motions on a fixed length scale. On the other hand, the viscoelastic relaxation time associated with the glassy modulus is almost constant at T g . These results suggest that the characteristic length scale for motions associated with the relaxation of the glassy modulus varies significantly for the three polymers studied. Trends in the KWW β values which describe probe reorientation support this interpretation