Scaled quantum mechanical force fields (SQMFFs) have been calculated for both isolated methanol and water-solvated methanol using both self-consistent reaction field (SCRF) calculations and supermolecule calculations performed on methanol hydrogen bonded to one, two, three, and four water molecules. Results obtained at the Hartree-Fock (HF) 4-31G, MP2 (second-order Moller-Plesset) 6-311G**, and density functional theory (DFT) (4,4;4,4) (7111/411/1*) levels are compared. A typical average standard deviation between measured and calculated frequencies for four isotopomers of methanol in both isolated and solvated states, and for all force fields, is 12 cm(-1). (The term "isotopomer" is used here to refer to isotopic species of a molecule that differ only by one or more isotopic atoms.) Excluding CH stretching frequencies, a typical average standard deviation is 7 cm(-1). Water solvation most strongly affects the CO stretching and OH bending frequencies, shifting the CO stretch down by 15 wavenumbers and the OH bend up by 70 wavenumbers. The SCRF calculations appear to correctly model the effect of solvation on the CO stretch, but not on the OH bend. The supermolecule calculations appear to correctly model the effect of solvation on the OH bend, but not on the CO stretch. Supermolecule normal mode calculations show artifacts due to vibrational coupling with water molecules in hydrogen-bonded rings. We remove these artifacts by deleting the Cartesian force constants and coordinates for water molecule atoms prior to transformation into internal symmetry coordinates. This change preserves the effect of solvation on electronic structure. Scale factors from the DFT calculations are closer to unity. The scaled force constants from both the MP2 and the DFT calculations are quite similar to those obtained at the lower HF level, indicating that scaling can fully compensate for errors in force constants obtained at the Hartree-Fock level.