Thank you Pete and Chemist B. Pete's answer is exactly what I was looking for. However, using Chemist's INDEX MATCH method opens up a level of precision and flexability that I previously thought was impractical. I'll spend some time understanding INDEX and MATCH in more detail... my first learning challenge is going to be to understand and fix the supplied function or my implementation so that it doesn't return "#VALUE" when dropped in the supplied spread sheet. Thank you both for your help.