Ingredient particle size (PS) affects digestibility and subsequent poultry performance. The objectives of this study were to determine the effects of reducing soybean meal (SBM) PS on hammermill energy use, broiler performance and apparent ileal amino acid digestibility (AIAAD). In experiment 1, four hammermill screen sizes were used to reduce extruded SBM PS. Three replicate batches of SBM were passed through each hammermill screen, totaling 12 batches of SBM. Hammermill motor amperage was recorded every second throughout each replicate. Each screen represents a treatment (trt). The screen sizes were 7.9 mm (trt A), worn 5.6 mm (trt B), new 5.6 mm (trt C), and 2.4 mm (trt D). Nine replicate PS analyses were conducted per trt. In experiment 2, 480-day-old Ross 708 male broilers were housed in battery cages with 12 replicate cages per trt. Treatments were arranged in a randomized complete block design with a cage of 10 broilers serving as the experimental unit. Birds were fed a mash starter diet from 0-10d and a mash grower diet from 10-20d. On d21, three birds per cage were euthanized via cervical dislocation and contents of their distal ilea flushed into a cup using distilled water. Feed and digesta samples were analyzed for titanium dioxide and amino acid concentrations. At the mill, electrical current draw by the motor (amps) and power usage (watts) were similar for trts A, B, and C while trt D drew the most current (P<0.0001) and power (P<0.0001). The PS was similar for A (891.85 μm), B (861.12 μm), and C (735.41 μm); however, D generated the smallest PS (463.88 μm) (P=0.0163). Soybean meal PS did not affect LWG, BW, or FCR from d1-21. Overall (d1-21) FI was highest for trts A and B and lowest for trt D. Treatment C was intermediate (P=0.0494). Soybean meal PS affected both essential and non-essential amino acid di- gestibility (P<0.05). The essential AIAAD was similar for trts A, B, and C and lowest for trt D (P<0.0001). The non-essential AIAAD followed a similar pattern (P<0.0001).