Voluntary support of higher education in America is investigated through regression analysis of institutional characteristics at two points in time. The assumption of donor rationality together with explicit consideration of interorganizational relationships offers a coherent framework for the analysis of voluntary support by the major donor-groups. Support by alumni and non-alumni individuals and business corporations is specifically isolated, and support by all other sources is combined in another category. Although the various donor groups sometimes act in a consistent manner, more often donor behavior is best understood on a subgroup basis. Institutional size is of importance to most donor groups, and institutional quality is of significance to all groups, save alumni, who respond to more institutional prestige and the financial difficulty of their alma mater. Current institutional efforts at fund raising appear to be primarily reactive in nature. Long-standing ties to institutions are of importance to most donor groups. The various groups who contribute to American research universities act in a manner largely predictable from theory. Economic organizations tend to react primarily in rational economic fashion, whereas the emotives of private individuals have a clearly human dimension as well. Contains 19 references. (SM)