Economizers are a common HVAC process with the potential to deliver significant energy savings by using outdoor air cooling to offset internal loads. But evidence from the field suggests that their track record is not good in terms of delivering those savings. This talk will provide a field perspective on some of the issues behind the poor track record, frequently illustrated with mini-case studies, and will conclude with a case study of a dysfunctional economizer in a cold environment and how the problem it was having was corrected by applying some of the concepts discussed earlier in the talk.