The objective of this study was to determine the palatability, feeding safety, growth performance, and replacement value of field pea (FP) for oats in yearling American Quarter Horses. Forty-eight yearling horses averaging 338.2 +/- 0.67 kg were used in a two-year replicated (84-d) study. The horses were randomly assigned based on sex and body weight (BW) to three pelleted experimental growing supplements: 1) 100% Oats and 0% FP (C), 2) 66.7% Oats and 33.3% FP (33.3PEA), and 3) 33.3% Oats and 66.7% FP (66.7PEA). The horses were fed a predetermined amount of alfalfa-bromegrass cubed (pelleted) hay. The supplement fed daily was divided into two meals and fed at 08.30 and 14.00 hours. Horse's BW, body length (BL), wither height (WH), hip height (HH), heart girth circumference (HG), cannon bone circumference (CB), forearm circumference (FA) and gaskin muscle circumference (GM) were taken at 28, 56, and 84 d. There was no statistical difference between supplement treatments for horse average daily gain (ADG) or final BW (P>0.10). There was a linear effect identified for 28, 56, and 84 d periods (P<0.01) for all treatment measurements. There was no statistical difference between supplement treatments for BL, WH, HH, HG, CB, FA, and GM (P>0.10). There was no evidence of discomfort, colic or hoof laminitis identified. When fed as two meals separated by 6 hours, FP was a suitable replacement for oats in yearling horse growing supplements up to a maximum of 66.7%.