The approval by USDA of glyphosate-resistant alfalfa in 2011 has necessitated a discussion of coexistence; the key issue being whether gene flow from genetically-engineered (GE) alfalfa would negatively impact organic or conventional farmers who reject GE alfalfa.  This was the subject of several lawsuits and an extensive USDA environmental review during 2006-2010. Glyphosate-resistant alfalfa is the GE trait of concern currently, but coexistence issues will pertain to future GE introductions as well. A framework for allowing coexistence of diverse production systems involving GE alfalfa is suggested. Successful coexistence may be defined as the ability of diverse production systems (organic, GE-adopting, conventional) to thrive without excessive neighbor influence, or resorting to extraordinary protection measures. GE-sensitive growers are those whose crop or cropping system would be negatively impacted by the presence of a GE trait as a contaminant.  To date, the primary GE-sensitive alfalfa production systems in the US are for export or organic markets, which are about 2% and 1% of US hay production, respectively.  For alfalfa seed, exports are the major sensitive market.  Clear distinctions need to be made between alfalfa seed and forage production, which have significantly different production systems which impact gene flow, and significantly different market sensitivities.  In the US, 99% of the alfalfa acreage is destined for forage production, 1% for seed.  Successful coexistence necessitates 1) an understanding of the factors surrounding pollen-mediated gene flow and other forms of contamination,  2) an understanding of the sensitivity thresholds of specific markets, 3) development of specific production, harvest, processing, and/or sanitation strategies to prevent contamination, 4) development of process-based certification methods to meet market demands, and 5) infrastructures to promote cooperation and communication among diverse parties and to resolve disagreements. The key attributes of coexistence strategies for alfalfa include isolation distances, crop management strategies including harvest management, product identification and testing methods, certification options, and the ‘soft values’ of mutual respect and willingness to cooperate among parties.  Coexistence is a partly biological and partly human behavior question, since market sensitivities and willingness to cooperate within the industry are dependent upon human behavior.  While the concept of ‘right to farm’ and coexistence between neighbors is not new to agriculture, the introduction of GE crops and their potential influence on neighboring farmers requires attention to improved coexistence strategies.