Introduction Recognized as one of the world's most ancient food crops, barley has been an important cereal crop since the early stages of agricultural innovations 8,000 to 10,000 years ago. Throughout history, barley has undergone continuous manipulation in an effort to optimize its use for human consumption and as animal feed. Barley has been used as a model organism in experimental botany, the plant of choice because of its short life cycle and morphological, physiological, and genetic characteristics. Globally, barley ranks fourth among cereal crops in both yield and acreage, after wheat, rice, and maize (Munck 1992b). With advances in food production and agriculture, major dietary shifts from barley to rice and/ or wheat have resulted in the decline in barley consumption, with the exception of societies — particularly those relying on traditional, small-scale agricultural systems — in which its use as human food has continued to the present. The world has now "re-discovered" barley as a food grain with desirable nutritional composition including some medicinal properties. Barley breakfast foods and snacks are increasingly available, driven by recent research findings, which show that barley fiber contains beta-glucans and tocotrinols, chemical agents known to lower serum cholesterol levels (Burger et al. 1981; Anderson et al. 1991). In Ethiopia, barley is the third most important cereal crop next to teff and maize. It is the staple food grain for Ethiopian highlanders, who manage the crop with indigenous technologies and utilize different parts of the plant for different purposes. Efforts to improve barley have demonstrated a preference for a limited number of modern, genetically uniform cultivars suited for high input agriculture, to the neglect of the various farmers'varieties, or landraces, on which a large sector of the human population has subsisted for millennia. The trend has narrowed the genetic base of the local material, leading to the gradual replacement of landraces with modern barley cultivars or of other crops such as wheat and oats. One consequence of this replacement is the loss of indigenous knowledge associated with replaced landraces. It is noted that some earlier morphotypes of Ethiopian barley (e.g., hooded barley; Bell 1965) are no longer found in cultivation. Some Ethiopian barley types (e.g., smooth awned types, hull-less types) kept at the Gatersleben gene bank in Germany (Index Seminum 1983) are not found in the country at present. Some varieties reported as abundant during the Vavilovian expedition (many naked and some rare covered forms) (Orlov 1929) could not be found in those areas (Asfaw 1988). The global trend has been to select for a few high yielding types, thus narrowing the genetic base of a crop. This trend has influenced the direction of Ethiopia's limited barley research over the past four decades. In crop genetic resources conservation efforts, Ethiopian barley has been identified as a priority crop since the 1920s, and extensive germplasm collections have been deposited in gene banks all over the world, especially in Russia and the U.S. (Orlov 1929; Ciferri 1940, 1944; Negassa 1985). Both the usefulness of barley and its high genetic and morphological diversity have rendered barley conservation a matter of top priority. This is evidenced by a long history of conservation in gene banks around the world since the 1920s, beginning formally in Ethiopia in 1976. Ex situ germplasm conservation has facilitated the preservation of the diversity present at a given point in time, but does not preserve the dynamic co-evolutionary processes that take place when landraces are continuously cultivated in their natural agroecological settings. To remedy this shortcoming, the need for complementary in situ conservation has been recommended and is under serious consideration (Feyissa 1995; Soleri and Smith 1995; Altieri and Montecinos 1993). Scientists are currently working to improve barley using genetic engineering and other modern techniques; they are looking forward to the formulation of barley ice cream and many other fabulous products for future markets. Another area of research concentrates on alternative approaches for sustainable use and conservation of the diversity in the barley gene pool. This approach focuses on in situ conservation of barley landraces — a new line of thought rooted in the traditional practices that have preserved the indigenous farmers'varieties. Traditional farming systems have the dual functions of production and conservation since the entire agroecosystems are crop germplasm repositories (Altieri and Montecinos 1993). This chapter highlights the case of barley in Ethiopia, focusing on the importance of traditional management and cultural practices associated with the landraces. Traditional farmer practices are viewed in the light of on-farm conservation activities being implemented under a new landrace on-farm conservation project, A Dynamic Farmer-Based Approach to the Conservation of Ethiopia's Plant Genetic Resources, supported by the Global Environment Facility and implemented by the Biodiversity Institute of Ethiopia in collaboration with other institutions.