Thanks to all who responded. I think the SUM(IF....) suggested by Pete_UK is what I want. I also want to do AVERAGE and MEDIAN on the same range, as well as add more conditional selection criteria. Thanks also for the tip about the "Evaluate Formula". I finally found it under Tools>Formula Auditing. Also, what is the "explicit coercion of Boolean arrays" mentioned by Donkeyote?

Thanks again - I will be working on these formulas during the next week.