Technical Abstract: Low crude protein (CP) concentration in corn (Zea mays L.) forage is its major limitation in dairy rations. This experiment was designed to determine if intercropping corn with climbing beans is a viable option to increase CP concentration in forage rather than purchasing costly CP supplements for dairy cattle rations in Wisconsin. In these experiments, 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 in early May and late April in 2004 and 2005, respectively and later thinned to 55,000 (low density) or 82,500 (normal density) plants ha-1. Beans were sown in rows 8 cm on one side of the corn rows at 82,500 plants ha-1 two or four weeks after corn planting. Averaged over four environments, mixture forage DM yields were similar, however the velvet bean and scarlet runner bean mixtures produced significantly higher forage DM yield in the late bean planting treatment. Mixture forage DM yields were significantly higher in the normal corn density treatment (21.0 Mg ha-1) compared to the low corn density treatment (17.2 Mg ha-1). Proportions of bean in the mixtures were: lablab bean 11.4%, scarlet runner bean 5.2%, and velvet bean 10.3%. Beans increased the CP concentration of all mixtures, except the scarlet runner bean mixture, with the greatest increases from the lablab bean (13%) and velvet bean (16%). Only the velvet bean mixture was significantly lower in calculated Milk ha-1. These experiments show that lablab bean grown with corn has the greatest potential of the three beans to increase CP concentration above monoculture corn, without compromising forage yield or calculated milk ha-1 and increasing feedstuff break-even nutrient value.