The genetics of five phenological and vegetative characters of the winged bean (Psophocarpus tetragonolobus (L.) DC.) were studied in the Fi generation of a half-diallel cross between nine diverse genotypes. Results indicated that high genetic variability existed for all traits. The narrow sense heritability estimates for time to flower and leaf size were 0.731 and 0.796, respectively. Consequently, considerable genetic advance could be expected by selection following hybridization for these two traits. Incomplete dominance for early flowering was observed. Transgressive heterosis was apparent in the Fi progeny for time to maturity, leaf size, leaves per plant and the leaf area index.