Angular-reflectance measurements were performed on several retroreflectors: metal-backed solid cube-corner arrays, metal- backed microspheres, and bare microspheres. Their peak values were 140% msr-1, 30% msr-1, and 2.0% msr-1, respectively. An instrument for measurement of angular reflectance is described. Methods for characterization of retroreflectors are developed for the purpose of predicting radiance and image contrast. Issues related to the minimum and maximum range of detection are discussed. Angular reflectance characteristics of cube-corners and microspheres are measured and discussed.