The effects of varying belt screen operational parameters on separating farmers stock peanuts (cv. Florunner), loose shelled kernels (LSK), and foreign materials (FM) were evaluated. The operational parameters evaluated were four screen deck lengths (40.6, 81.3, 121.9, and 162.6 cm); four belt spacings (0.87, 0.95, 1.03, and 1.11 cm); four belt speeds (81.3, 91.4, 101.6, and 111.8 cm/sec); and four feed rates (0.45, 0.91, 1.36, and 1.81 t/hr). The amount of materials falling through the screen varied directly with screen deck length and belt spacing. Screen deck length had the greatest effect on the amount of LSK, total FM, sticks from FM, dirt from FM, and rocks from FM falling through the screen. Belt speeds and material feed rates had less effect on the separations made than screen deck length and belt spacing.