Summary: Methods have been described for the routine production of type-specific antipneumococcic rabbit serum for therapeutic purposes. The methods for the immunization of rabbits, processing of the serum, determination of toxicity, standardization, etc. have been given in detail. Certain experiments have also been reported which form the bases for the development of the methods described. It is suggested that antipneumococcic rabbit serum be standardized on the basis of specific antibody content in milligrams as determined by in vitro methods in order that precise amounts may be administered and so that the specific antibody content of antiserum of one type may be related to that of another.