The phase behavior of a model polymer solution, polystyrene in methyl aceate, has been investigated by means of static light scattering. Rayleigh ratios and correlation lengths have been measured over a broad range of temperatures (300-400 K) and concentrations (0.5-10.3 wt %). A novel procedure to correct the measured forward scattered intensity for turbidity has been applied. Rayleigh ratios have been used to determine values of the free energy curvature (d2AG/dc2) in the homogeneous one-phase region of this system, i.e., between the upper and lower critical phase boundaries. The complete data set forms a unique basis which can be used to test thermodynamic model predictions.