Phase III of the collaborative study of methods of assay for nutrients in infant formulas was conducted. The study included assay of chloride, phosphorus, proximates (ash, fat, protein, total solids, and carbohydrates), thiamine, total pantothenates, and vitamins A, B12, and E. Most of the methods were those in Official Methods of Analysis, 13th edition, with slight modifications, or methods of the Infant Formula Council. On the basis of the results obtained by the collaborators, the methods for chloride, phosphorus, proximates, thiamine, and vitamin B12 have been adopted official first action. Methods for total pantothenates, vitamin A, and vitamin E were not recommended for adoption at this time because of anticipated improvements in methodology in the foreseeable future.