This chapter presents a comparison of three of the most capable and popular software packages for structural equation modeling (SEM), Amos, EQS, and LISREL. The programs are compared in regard to available input formats, output formats, and many technical options, including options concerning the methods of estimation. Results suggests that the three packages typically provide equivalent results. However, they differ, for instance, in how they handle admissibility problems. The programs also differ in documentation. All three programs contain options that are not even mentioned in the manuals. All three programs are very capable. Thus user preferences may reside in program characteristics unrelated to SEM.