Bi-directional reflectance is a fundamental surface property that has received a great deal of attention, particularly during the early years of the space program. Although the value of using accurate surface property data has always been recognized, bi-directional reflectance information is rarely used because of the sheer volume of data involved. Now, with powerful workstations readily available, large Monte Carlo codes can be run very quickly and full advantage can be taken of the detailed surface property description provided by bi-directional reflectance data. This paper provides a detailed description of a simple, compact, flexible apparatus for measuring bi-directional reflectance and a review of measurement considerations.