In order to establish proper guidelines for cooperative purchasing of supplies and equipment by school districts in association with other school districts, a statistical study was undertaken. Public school districts in the U.S. which had combined their purchasing power were identified and eighty-four organizations were classified according to--(1) geographic location, (2) composition of membership, (3) number of students, (4) number of years in operation, and (5) items purchased and money expended. Materials furnished by these organizations as well as materials obtained from the literature were employed in the construction of an interview guide to be applied to ten selected purchasing organizations which were the objects of the main study. Tentative guidelines were prepared as a result of interviews and these were validated by submitting them to the person with the most expertise in each of the 84 organizations. A guideline was accepted if it was found by the Chi Square Test to be significant at the .05 level. Sixty-three guidelines were accepted. (NI)