Bio-fortification of beans can sustainably and substantially increase iron (Fe) and zinc (Zn) in the diet, and so reduce ailments associated with their deficiencies. Despite the large consumption of beans in Rwanda and Uganda occurrence of these ailments remains high. There is therefore a need to increase consumption of high Fe and Zn beans in these countries. This however requires that varieties rich in these micronutrients be developed. For this to be done, the genetics of micronutrient accumulation in beans must be studied. Stability of these nutrients across environments and the reaction of the potential varieties to common biotic stresses also need to be known. These aspects made up the objective of this study. This book clearly shows the potential to obtain and improve bean varieties for iron and zinc content in farmers preferred varieties. Iron and zinc content was quantitatively inherited and not independent. G X E effects on iron and zinc content are highly significant. Some of the nutrient rich bean varieties possess good and beneficial traits. The book also displays important genetic principles that guide breeding decisions.