Misforecasting demand will cost profits and threaten reputations, market share, and even the business itself. Roland Martin and Stephan Kolassa draw on their expertise with retail companies to examine the major challenges for demand forecasting and the choices the demand forecaster must make. Their consideration of the options provides a valuable guidepost to the demand forecaster in measuring demand, handling questionable data, making adjustments to automatic forecasts, and choosing appropriate performance metrics. Copyright International Institute of Forecasters, 2013