This report describes tests performed on members of ASTM A441 steel as part of a project which has as its aim the extension of plastic design procedures to include steels of up to 50 ksi yield strength.The testing program consisted of basic material property tests, beam tests under uniform moment and moment gradient, and beam-column tests. In the tests on beams and beam-columns, emphasis was placed on determining the influence of lateral-torsional and local buckling on the member behavior.