The original drawings and published designs for town houses by Robert de Cotte are examined here in order to clarify a relatively unknown aspect of his activity as one of the dominant figures in French architecture of the early 18th century. The projects, which date from 1710 to 1716, are set against the background of the history of the hôtel, a distinct architectural type that underwent a remarkable period of development in Paris during the first three decades of the century. New light is shed on the architect's attitude toward the urban mansion by a virtually unknown series of designs in the Bibliothèque Nationale, Paris. Taken as a group with the executed plans, they demonstrate that de Cotte's ability lay not in the development of new ideas but in synthesis of a very high order-his sources were primarily the works of J. H. Mansart and Lassurance. His designs are distinguished by a consistent interest in giving the corps-de-logis the appearance of a freestanding block. In the elevations, he concentrated on harmonious compositions with suavely detailed motifs, achieving an elegant simplicity entirely his own. The relation of his plans to the functions of an hôtel, as revealed in house-building manuals of the period, shows that de Cotte sought to satisfy both the public and private needs of his clients.