Wild emmer wheat, Triticum turgidum subsp. dicoccoides, (2n = 4x = 28; genome BBAA), the progenitor of domesticated wheat, is genetically very close to durum and common wheat. This wild taxon has many characteristics that would be valuable if transferred to domesticated wheat. An appropriate exploitation of the "wild" genome requires its dissection into segments and evaluation of the contribution of each segment separately to the performance of domesticated wheat. This work describes the production of a series of chromosome-arm substitution lines (CASLs) of wild emmer in the background of the Israeli common wheat cultivar Bethlehem (2n = 6x = 42; genome BBAADD). The identity of the "wild" arm in each CASL was confirmed through the use of RFLP and SSR markers that were polymorphic between the two taxa. The product of this work is a series of true-breeding agronomic lines the breeding value of which can be evaluated under field conditions in different geographic regions. The usefulness of CASLs in studying the improvement of qualitative and quantitative traits in wheat is discussed.