An outline is given of the study of diversity reception being carried out jointly by the Signal Corps Engineering Laboratories and Washington University, the purpose of which is to determine the characteristics, limitations, and relative merits of space, polarization, and frequency diversity systems. Results are reported on various systems including dual- and triple-spaced-antenna diversity and several forms of polarization diversity. Frequencies in the range of 7 to 16 Mc have been investigated over a 900-mile path between New Jersey and St. Louis, Missouri. Improvement provided by the various diversity systems is presented graphically in terms directly applicable to the design of a transmission facility and the variability in improvement is indicated for its value in estimating departure from mean performance.