About 150 kha of grain legumes are grown annually in the U.K. Of these, 62% are planted with Pisum sativum, 30% with Vicia faba and 8% with Phaseolus spp. Pisum and Vicia are temperate in origin, nodulate freely in the U.K. without inoculation and fix sufficient nitrogen to support high yields. In Vicia, nodules formed on autumn sown plants can overwinter and begin N<latex>$_2$</latex> fixation at the time that spring sowings are made. Yield in Vicia and Pisum is likely to be limited by factors other than N<latex>$_2$</latex> fixation. Phaseolus vulgaris nodulates erratically in the U.K., and even when well nodulated needs the addition of some nitrogenous fertilizer. Its mean temperature for growth and its nodule physiology reflect its tropical or subtropical origin. However, there are good prospects for selecting cool-tolerant host cultivars and for crossing with the more cold-tolerant Phaseolus coccineus. Rhizobium phaseoli, which nodulates Phaseolus, has considerable homology with R. leguminosarum, which nodulates Vicia and Pisum, and the two can be crossed. Breeding suitable rhizobia for the cold-tolerant host selections is a real possibility. Glycine max, which is closely related to Phaseolus, is much less well adapted to cool conditions; its endophyte (R. japonicum) does not occur in soils in the U.K. and has little homology with temperate rhizobia.