Instructional design and educational evaluation have emerged within the last century as formalized systems pertinent to the creation of education and training. The practices of instructional design and educational evaluation should be symbiotically related. But they have become academic silos, which has contributed to a lack of progress of theory and practice in both areas. Design practice is the main loser in this separation of interests. This chapter proposes that a more detailed examination reveals the natural value of this relationship, which may lead to advances in the understanding of design. In turn this may lead to advances in the teaching of design and evaluation. Evaluation has two embodiments in practice: it is a process of examining the details of a product, process, or phenomenon in order to judge its value, and it is a process carried out during and after instructional design for the purpose of quality control, administration, and product improvement.