Phaseolus vulgaris, also known as dry-bean, is an important legume that is grown in North America as a major source of dietary protein. Rhizobium etli is gram negative bacterium that is capable of entering into a symbiotic relationship with Phaseolus vulgaris providing the plant with a source of biologically reduced nitrogen. However, beans that are grown as a crop in Canada are typically fertilized using industrially derived nitrogen. This thesis describes that adaptive evolution can be used as a technique to develop inoculum strains that can be used with varieties of bean currently grown in Canada. R. etli CFN42 is a sequenced strain that is being used as a model organism to study plant-microbe interactions and nitrogen fixation. Although it interacts with current bean cultivars, it does not form an effective symbiotic association. Following an initial inoculation onto Phaseolus vulgaris cv Envoy, only small, white ineffective nodules that did not fix nitrogen were observed. These nodules were harvested and used as an inoculum on a new set of plants. The results suggest that repeated cycling of nodules can lead to the isolation of effective strains. Our data show that R. etli CFN42 initially produced nodules that were white and found on the peripheral roots, whereas strains that were isolated by cycle 3-4 were capable of developing crown nodules. Repeated cycling of these nodules led to strains that appear to produce pink and effective nodules by our 8th inoculation cycle. The majority of the isolated strains had faster growth rates with doubling times of about 5.3  0.6 hours whereas CFN42 had a doubling time of 8.7  0.6 hours. This effectiveness was reflected both in the dry weights of the plants, as well as the quantitation of nitrogen fixation by acetylene reduction.