Proliferation of prescriptive models in an "engineering" field is not a sign of its maturity. Quite the opposite. Materials engineering, for example, meets the criterion of parsimony. Sadly, the very large number of models in "instructional design," putatively an engineering field, raises questions about its status. Can the multiple varied prescriptions for the same type of learning be taken as a sign of the field's maturity? Negotiating the physical world would be far more precarious if materials engineering were similarly burdened. In its case what precludes that derives from a limited number of agreed-upon basic principles. Given that its mission is to design and produce Instruction that predictably leads to predetermined outcomes, instructional design may be thought of as an "engineering" field. If it is to live up to the "engineering" label, becoming a field similar in stature to, say, materials engineering, it too will require an economical "science" underpinning. Occam's razor. That today it lacks such a foundation will be freely acknowledged. Absent is any empirical validation of relationships among a model's design parameters. For that kind of detail is what it would take to provide convincing support for its specific prescriptions. Nor are there even evaluations of models in their entirety. Today a model's stature rests on the stature of the rationales offered in its support. And there are today many such differing models with differing, even convincing, rationales. In the absence of data, how to choose among them? It is possible to say that model formulation has reached bubble proportions. The field is patently in need of trimming. It is in need of as small a number of agreed-upon principles as would be consistent with fulfillment of its mission. What is needed, much as was the case at instructional design's early history, is a narrowly focused research agenda. Each contending model needs to be able to point to documented principles that support it. That requires experimentation. Rationales alone would no longer be recognized as the sole currency. Any engineering field requires no less. The present article, addressing this issue, describes as a first step an approach for generating evaluation data. It describes a proposed broad-brush "initial" approach to model evaluation. It would be applicable to any model. Serving as a screening device, it could set the stage for a later more finely tuned "basic research" agenda.