Plant attributes involved in weed suppression are difficult to define because of the complexities associated with crop-weed competition.  An indirect assessment study was conducted to determine the relationship between seed size and putative weed competitive and agronomic traits in spring wheat.  Eighteen genotypes comprising two contrasting groups, eleven large seeded, broad in origin accessions, and seven locally adapted varieties were evaluated under mono-crop conditions at Kalispell and Huntley, MT during 2003 and 2004.  Genotype and relevant trait data were subjected to principal component and cluster analyses for uncovering patterns of association among traits and discriminating among genotypes.  The observed patterns differed among environments, explaining from 49% to 68% of the variation in the dependence structure.  These patterns suggested that seed size is positively associated with early emergence, early biomass accumulation, and increased light capture during early growth.  The association of seed size with agronomic, phenologic, and physiologic traits was in general moderate.  Most large seeded accessions showed increased early biomass accumulation, increased plant height, extended grain filling, and had acceptable agronomic performance.  The observed interrelationships might have practical implications in breeding for weed suppressive ability.