The art and science of concrete construction has a long history, dating at least to ancient Rome. The development of reinforced concrete, on the other hand, is relatively recent, being scarcely one hundred years old. Numerous men and organizations in Europe and the United States have made major contributions to the understanding and use of reinforced concrete, and our purpose here will be to provide a quick review of some the high spots. Jean Monier, a French gardener who knew nothing about engineering or architecture, has long been given credit for the first use of reinforced concrete. Monier embedded wire nets in concrete to produce strong and durable tree and flower pots, and patented his process in 1867. Later, in the 1870's, Monier obtained patents on processes for building reinforced concrete pipes, reservoirs, floors, straight and arched beams, and bridges. During this developmental peroid of reinforced concrete construction, numerous men introduced systems, most of them under patent for the exclusinve benefit of their developers and promoters. One of the most successful systems was that perfected by Francois Hennebique in France, who developed a method of using two series of reinforcing rods. One of the series was straight, and lay in the lower part of the concrete. The other lay on the top and bent down near the center of the span to lie close to the straight rods. Hennebique also used flat iron stirrups in beams and slabs. His method, at th esame time, called for the casting of slab, beams, and columns as a single unit, and thus he has received credit for originating monolithic construction. With modifications, several features of the Hennibique system remain in use today. Between 1892 and 1899, Hennibique and the contractors licensed to use his system completed hundreds of reinforced concrete tuildings. Much of the experimentation and use of reinforced concrete had been on a trial and error basis. Matthias Koenen, in Berlin, Germany, was the first experimeter to deduce methods of computation for load tests, publishing his analysis of his theory of flexure on the following premises: (1) plane sections perpendicular to the neutral axis prior to bending remain so following bending; (2) stress is proportional to strain; (3) there is perfect bond between concrete and steel; and (4) tension stresses in the concrete are no considered. Koenen's basic procedure is still generally accepted and used today.