The pressure derivatives of the second virial coefficients [dA(2)/dP; 0.1 less than or equal to P (MPa) less than or equal to 35.0] for dilute polystyrene (PS) solutions in good, 0, and poor solvents were measured with static light scattering. The solvent quality improved (dA(2)/dP > 0) in the good and poor solvents that we investigated (toluene, chloroform; and methylcyclohexane) but deteriorated (dA(2)/dP < 0) in 0 solvents (cyclohexane and 50-50 cis,trans-decalin). The effects of temperature [22 < T (degreesC) < 45] and molecular weight [25 x 10(3) < weight-average molecular weight (amu mol(-1)) < 900 x 10(3)] on dA(2)/dP for PS/ cyclohexane solutions were examined. (C) 2003 Wiley Periodicals, Inc.