Quantitative trait loci (QTLs) affecting seed weight in pea (Pisum sativum L.) were mapped using two populations, a field-grown F2 progeny of a cross between two cultivated types ('Primo' and 'OSU442-15') and glasshouse-grown single-seed-descent recombinant inbred lines (RILs) from a wide cross between a P. sativum ssp. sativum line ('Slow') and a P. sativum ssp. humile accession ('JI1794'). Linkage maps for these crosses consisted of 199 and 235 markers, respectively. QTLs for seed weight in the 'Primo' x 'OSU442-15' cross were identified by interval mapping, bulked segregant analysis, and selective genotyping. Four QTLs were identified in this cross, demonstrating linkage to four intervals on three linkage groups. QTLs for seed weight in the 'JI1794' x 'Slow' cross were identified by single-marker analyses. Linkage were demonstrated to four intervals on three linkage groups plus three unlinked loci. In the two crosses, only one common genomic region was identified as containing seed-weight QTLs. Seed-weight QTLs mapped to the same region of linkage group III in both crosses. Conserved linkage relationships were demonstrated for pea, mungbean (Vigna radiata L.), and cowpea (V. unguiculata L.) genomic regions containing seed-weight QTLs by mapping RFLP loci from the Vigna maps in the 'Primo' x 'OSU442-15' and 'JI1794' x 'Slow' crosses.