The data from bar-code scanners offers a number of attractive features for economists and statisticians, because they are collected continuously, are available quickly and record prices for all items sold, not just a sample. But scanner data also presents a number of difficulties for current statistical systems. This book assesses both the promise and the challenges of using scanner data to produce economic statistics. Three papers present the results of work in progress at statistical agencies in the US, UK and Canada, including a project to incorporate scanner data into the monthly Consumer Price Index. Other papers demonstrate the potential of using scanner data to test economic theories.