Many of the world's largest companies are developing data warehousespending an average of three to five million dollars per project. Yet studies indicate that as many as 75 per cent of all data warehouse projects fail or are never implemented. Although data warehouses are a hot topic and essential for large corporations, this area is still relatively new and very few companies or consultants have the kind of real-world experience that can help them head off potential problems before they derail the project. This text provides a map through the mine field for anyone setting out to design, construct, and implement a data warehouse project. It aims to help those involved in a project to recognize, correct and prevent some of the most common mistakes and misperceptions.