Several alternative feedstuffs are available for use in weanling pig diets, but the standardized ileal digestibility (SID) of amino acid (AA) in most ingredients has not been measured in weanling pigs. The objective of this experiment was to measure the SID of AA in corn, soybean meal, corn gluten meal, high protein distillers dried grains, and field peas fed to weanling pigs. Twelve weanling barrows (initial BW: 10.3 ± 0.9 kg) were prepared with a cannula in the distal ileum and randomly allotted to a replicated 6 × 6 Latin square design with 6 diets and 6 periods in each square. Five diets were formulated using corn, soybean meal, corn gluten meal, high protein distillers dried grains, or field peas as the sole source of protein and AA. An N-free diet that was used to calculate basal endogenous losses of AA and protein was also formulated. Chromic oxide was included in all diets as an indigestible marker. All pigs were fed each diet for seven day and ileal digesta were collected during the last two days of each period. The samples were lyophilized and analyzed for crude protein and AA and the SID of all AA were calculated according to standardized procedures. The researchers concluded that the SID values of all AA in corn gluten meal were similar to that in soybean meal, however, the high protein distillers dried grains had SID values for AA that were less than in both corn and soybean meal.