The Raman spectra (3300 to 10 cm(-1)) of gaseous, liquid, and solid difluoromethylcyclopropane, C-C3H5-CF2H, and the infrared spectra (3400 to 60 cm(-1)) of the gas and solid have been recorded. The spectra of the fluid phases are consistent with two stable conformers in equilibrium at ambient temperature. These spectral data have been interpreted on the basis that the cis conformer (H atom of the difluoromethyl group is cia to the three-membered ring) is more stable than the gauche form in both the gaseous and liquid phases, and it is the only rotamer present in the solid. The mid-infrared spectra of the sample dissolved in liquid xenon as a function of temperature (-100 to -60 degrees C) have been recorded. Utilizing two conformer pairs, the enthalpy difference has been determined to be 102 +/- 8 cm(-1) (1.22 +/- 0.10 kJ/mol) with the cis conformer the more stable form. The enthalpy difference has also been determined to be 145 +/- 48 cm(-1) (1.73 +/- 0.57 kJ/mol) for the liquid from the temperature-dependent Raman spectra. The potential function governing the asymmetric torsion has been obtained and the determined potential constants are V-1 = 229 +/- 5, V-2 = 40 +/- 4, V-3 = 1270 +/- 3, and V-4 = -136 +/- 2 cm(-1). The cis to gauche barrier is 1255 cm(-1) (15.01 kJ/mol) and the gauche to gauche barrier is 1399 cm(-1) (16.74 kJ/mol). A vibrational assignment for the 30 normal modes for the cia conformer is proposed and several of the fundamentals for the gauche conformer have been identified. The structural parameters, dipole moments, conformational stability, vibrational frequencies, and infrared and Raman intensities have been determined from ab initio calculations. The predicted conformational stability is at variance with the experimental results even from the MP2/6-311+G(2d,2p) calculations. These experimental and theoretical results are compared to the corresponding quantities of some similar molecules.