Fourth International Conference on Constitutive Laws for Engineering Materials: Theory and Application In Mechanics of Materials, constitutive equations are the mathematical descriptions of material deformation behavior and are needed in analytical and numerical stress analyses. Different materials have different constitutive equations. Research in constitutive equations is usually associated with certain fields such as mechanical or civil engineering or others. Three previous conferences at the University of Arizona had constitutive equations of nearly all materials used in engineering applications as a theme. A follow-up conference is planned for summer of 1999 on the campus of Rensselaer Polytechnic Institute. This date also marks the 25th anniversary of a workshop on Inelastic Constitutive Equations held at RPI and sponsored by the Solid Mechanics Program of NSF. The proceedings of this workshop will serve as a gage for measuring progress. Support is sought for the travel expenses of invited speakers, graduate students and post-doctoral associates, and for publication of the proceedings. A separate budget financed by registration fees covers other expenses including announcements, preparation and conference organization.