Low crude protein (CP) concentration in corn silage is its major limitation in dairy rations. In this experiment corn was intercropped with three climbing beans: lablab bean [Lablab purpureus (L.) Sweet], velvet bean [Mucuna pruriens (L.) D.C.], and scarlet runner bean (Phaseolus coccineus L.), or grown in monoculture near Arlington and Lancaster, WI. Corn was sown at 82,500 (high density) or 55,000 (low density) plants/ha in early May. Beans were sown in rows six inches beside corn rows at 82,500 plants/ha, 2 or 4 weeks after corn planting. Averaged over locations and management treatments the lablab bean-corn mixture produced 19.9 Mg/ha of whole plant dry matter compared to 19.6 Mg/ha in monoculture corn, with no detectable differences among mixture treatments. Early bean planting had no affect on total mixture yield while the high-density corn treatment yielded 4.8 Mg/ha more than the low corn density treatment. Mean proportions of beans in the mixtures were: lablab bean 8.8%, scarlet runner bean 5%, and velvet bean 3.4%. Addition of lablab bean increased neutral detergent fiber concentration from 379 to 392g/kg and acid detergent fiber concentration from 196 to 212 g/kg in mixtures. Bean planting date had no significant effect on mixture CP concentrations, however mixtures with lower corn density contained 5 g/kg more CP than the high-density corn treatment. Beans increased the CP concentration of all mixtures, with lablab bean-corn mixtures containing 74 g/kg CP compared to 65 g/kg in monoculture corn. These data show that lablab bean grown with corn has the greatest potential of the three beans to increase CP concentration above monoculture corn, without compromising silage yield.