The objective of this study was to determine the competitive ability of different field pea cultivars against endemic weed populations present in organic cropping systems. Five field pea cultivars representing two distinct leaf types (normal and semi-leafless type) were chosen to evaluate field pea competitive ability against weeds. Weed suppressive ability was calculated at each growth stage, as well as the sensitivity of weed suppressive ability to changing weed pressure. Results showed that Cooper and Golden had better plant establishment than other three cultivars, even under poor germination conditions. Cultivars with low seedling mortality and good emergence were considered more competitive. Cooper and Golden had good emergence because of inherent seed vigor, which is probably a function of greater seed size. Thus, these two semi-leafless cultivars could be considered as more competitive cultivars, because they are more likely to form even competitive canopies under a wide range of environmental conditions.