Medication reconciliation arose as the solution to the well-documented patient safety problem of unintentionally introducing changes in patients' medication regimens due to incomplete or inaccurate medication information at transitions in care. Unfortunately, medication reconciliation has often been misperceived as a superficial administrative accounting task with a "pre-occupation with completing forms," resulting in the implementation of ineffective processes. In this article, the authors briefly review the evidence supporting medication reconciliation but focus more on key practical questions regarding the elements of an effective medication reconciliation process: what it should consist of, where and when it should occur, who should carry it out and how hospitals should implement it. The authors take the why of medication reconciliation to consist not just of the professional obligation to avoid causing harm, but also of a rational self-interest on the part of healthcare leaders. The authors argue that, rather than wasting time implementing a nominal reconciliation process, we should invest time and energy in a more robust and effective strategy, and they address specific practical questions that arise in such an effort.