There is bound to be a trace of nostalgia for the old 3,000 psi concrete mixes when the time comes that we must discuss 21 Newtons per square millimeter mixes. But it's only a matter of time- and probably not too long at that- before we will have to orient our thinking to metric measurement units. England has completed half of its 10 year conversion program. About 90 percent of the world's population operates on the metric system; the United States and Canada are the last major holdouts. Canada has already started to move toward metrication, and the metric study team of the United States National Bureau of Standards has just recently released its preliminary report. Estimates on the length of time required to effect such a change generally range from five to ten years. The conversion of our basic measurement system to that of S. I. will offer several advantages but will also entail some short-term disadvantages. The White Paper issued by the Canadian government, which officially set the country on the road to metrication has set forth the benefits, problems, and outlines for implementing the conversion. Its findings are valid for both Canada and the United States. Listed as the deciding advantages of the S. I. system are its simplicity, the opportunity it affords for rationalization and the opportunity to reassess methods of communication. One of the most compelling reasons for metrication is that it will enable us to fit our materials sizes into those used by other countries and thereby increase our sales abroad to bring about a more favorable balance of trade. Experts claim we are losing 25 billion dollars a year in export sales by staying with foot-pound English units. A motivation problem posed is that at present the U. S. construction industry is basically local in nature; it has little contact with foreign materials.