Predicting performance of electro-optical systems that operate while being subjected to thermal/mechanical loadings has been accomplished by integrating computer-based numerical tools. Honeywell has interfaced thermal, structural, and optical computer programs on both CDC 6600 and Honeywell 6080 computers into a Thermal/Structural/ Optical (TSO) evaluation process. The TSO process integrates the separate analyses by automatizing data transfers among the individual technology programs to permit rapid evaluation of optical systems undergoing thermal/mechanical loadings. The design/analysis process involves iterating the following: thermal/ mechanical error budgets, TSO evaluations of electro-optical systems, and comparisons of TSO results with error budget line items. This paper presents how the TSO process has interfaced the individual technology programs, examples of TSO applications to Honeywell electro-optics systems, and test data from systems that have been subjected to thermal/mechanical loadings. The thermal/mechanical loadings include cryogenic loads, steady state acceleration, random vibration, and decaying dynamic loads. The examples show how the process has been effectively used during the design/analysis stages of projects to evaluate alternate design concepts. The resulting process has resulted in a cost-effective methodology for predicting performance of electro-optical systems undergoing theral/mechanical loadings.