The special properties required of lubricants for refrigeration and air-conditioning compressors are discussed in chapter 32 of the ASHRAE Handbook—1980 Systems. This paper reviews laboratory and compressor screening and methods of evaluation for qualifying and controlling the quality of these lubricants. Important factors that determine functional requirements include the type of refrigerant, operating conditions, and compressor design considerations; which factors, in turn, define the lubricity, stability, solubility, and low-temperature properties that a successful lubricant must provide. The evaluation of petroleum-base stocks, synthetic fluids, blends, and additives in refrigeration lubricant formulations is discussed. The importance of relating bench tests to compressor tests and field experience is stressed.