More than any other mishap we have studied recently, the loss of the Mars Climate Orbiter highlights the need for comprehensive verification and validation. The Mars Climate Orbiter team did not ensure that software matched requirements. Because of this oversight, the team used software that reported the spacecraft's trajectory in English instead of metric units, a discrepancy that should have been caught by rigorous verification and validation. This problem was compounded by miscommunication, invalid assumptions and rushed decisions. On its journey to Mars, the spacecraft drifted away from the flight path its navigators were following. When the Mars Climate Orbiter reached its destination, it entered the Martian atmosphere well-below its intended altitude and disappeared. As we review the Mars Climate Orbiter this month, consider the progress we have made since this 1998 mission failure, but also look for parallel situations in the programs and projects you are working on today.