Densities were measured for mixtures of m-cresol + m-xylene and m-cresol + tetralin (1,2,3,4-tetrahydronaphthalene) at temperatures of 298.15, 323.15, and 348.15 K and pressures up to 30 MPa over the entire composition range. The Tait model was capable of correlating the density data accurately. Isothermal compressibilities of the fluids and their mixtures were calculated. It was also found that the excess volumes of m-cresol + m-xylene are negative and those of m-cresol + tetralin are positive over the investigated conditions.