Recent years have witnessed several important developments in: analysis of structures with finite element method for linear and nonlinear responses, design sensitivity analysis for linear and nonlinear responses, and optimization techniques in nonlinear programming. Exploitation of these developments in creating an integrated structural optimization system is warranted. Conducive environment for development of such a system is provided by high speed computers, CAD/CAM/CAE, efficient database management systems, parallel processing, automated design processes, etc. Such capabilities have created an environment to combine available general purpose finite element softwares and design optimization techniques into an integrated set. STROPT, the structural optimization system is a program evolved through usage of these potential features. The paper presents problem formulation, methods of design sensitivity analysis, program architecture, capabilities, and useful features of STROPT. Optimum designs of small and large scale structures comprising of beam, shell, laminated composite and other types of finite elements are also given.