The paper reviews the worh of Paul Cottancin, a French structural engineer working at the turn of the century. The Cottancin system of reinforced concrete, which is based on the use of woven wire placed in relatively thin concrete sections, is described, us is his use of reinforcement in both brickwork and glass. A list of buildings and structures for which Cottancin acted us engineer is given, and five of these are described in some detail. It is concluded thut greater study of the history of structural engineering by engineers would be unlikely to ,familiarise them with the work of Cottancin; also that, although some of his ideas are highly unusual, the concepts he used regularly (e.g. deep beam action, wall-floor combined action) are less well used today than they could be.