In an effort to clarify the effect of dynamical heterogeneity on the glass transition in binary systems, we measured the heat capacity C-p on concentrated toluene solutions of polystyrene (PS) using an adiabatic calorimeter. We also carried out dielectric measurements on the same system. Results indicate that the C-p vs temperature T curve of the solvent toluene/xylene(90/10) exhibits a sharp stepwise increase of C-p at the glass transition temperature T-g (= 115 K). In contrast, the C-p curves of PS/toluene solutions exhibit a double-sigmoidal shape. The configurational heat capacity DeltaC(p) around T-g has been determined by subtracting the heat capacity due to the lattice vibrations and intramolecular vibrations. We have further resolved DeltaC(p) into two sigmoidal curves using an empirical function. The T(g)s corresponding to the two sigmoids are denoted as T-g1 and T-g2 (T-g1 > T-g2). Two dielectric loss peaks termed alpha and beta are assigned to segmental motions of PS and rotation of the toluene molecules, respectively. The dielectric glass transition temperatures T-alpha and T-beta are defined as the temperatures at which the dielectric relaxation times for the alpha and beta processes become 10(3) s, respectively. T-alpha and T-beta agree well with the calorimetric T-g1 and T-g2, respectively.