Because much difficulty has been experienced with wing flutter or unstable torsional oscillations on large monoplane wings, the question of torsional rigidity has come to be one of great concern to designers of monoplanes. This project is limited to a study of ways and means of furnishing the torsional rigidity demanded by aerodynamic considerations. The problem is being attacked both experimentally and analytically. Part I deals with the experimental work thus far carried out. In Part II is given an outline of the progress which has been made to date on the theoretical or analytical study. The principal objects of this study are as follows: 1. To determine the type of wing structure which, for a given weight, has the greatest torsional rigidity. 2. To develop a method by which any type or size of wing structure can be analyzed to determine its actual torsional rigidity more accurately and quickly than is possible by the best methods known at the present time. 3. To determine which members of a metal truss type wing structure are the most important in regard to their contribution to the torsional stiffness of the structure. 4. To discover some definite laws, according to which a wing frame deflects under torsional loads, that can be relied upon generally for use in the aerodynamic solution of the cause of wing flutter, and which can be used for designing a wing to give stable deflections.