Systems migration is a fact of life in the library world for various reasons. One of the more recent challenges spurring integrated library systems (ILS) upgrades comes when patrons find new functionality on other Web sites and then expect to search library sites in the same fashion. The migration process entails the following stages: system selection, implementation planning, system profiling, data conversion, training, and publicity. In this article, the author addresses the two stages that are most critical to a smooth, successful migration--system profiling and data conversion. The author elaborates on the tasks and staff involvement required in each stage, and gives advice on how to perform each of these tasks.