When managers are unable to use quantifiable time series data to make forecasts or decide on uncertainties, they can either rely on their own intuition and judgment or resort to the insights of others. The Delphi technique is a well-known forecasting technique that relies on the pooled perspectives of experts to predict uncertain quantities or the outcomes of events. This relies on polling the opinions of experts, aggregating these opinions, feeding them back to the responding experts along with their own estimates, and having them repeat their judgment calls until some level of consensus is reached. More recently, however, the opinions of many others who are not experts have been sought on a range oftopicsin a loose assembly of similar techniques bundled under the title of crowdsourcing. This article compares Delphi and crowdsourcing as prediction and estimation tools for managers. It notes their differences and similarities, and provides a simple tool for executives to use in deciding whether or not to use these tools, and if so, which tool or combination of them will work best in a given situation. # 2016 Kelley School of Business, Indiana University. Published by Elsevier Inc. All rights reserved.