In our continuing effort to incorporate state-of-the-art technologies into our services, Fluor Daniel evaluated some of its engineering activities to determine which ones will benefit the most from Expert Systems (ES) technology. Prototype Expert Systems were developed for selected activities such as conceptual cost estimating, project scheduling, hazard analysis, process control, etc. The objective of prototyping was not only to provide proof of concept, but also to identify a suitable expert system shell which would enable cost-effective Expert System development. Our experience demonstrates that an Expert System shell based on object-oriented knowledge representation is more suitable for some engineering applications than a purely rule-based system. We also found that the general purpose tools we used do not have the graphical capability necessary for some engineering applications and that the DBase interface and reporting capability need improvement.