Data cleaning has not been a very active area of research. Perhaps the problem was too messy to deal with,too hard to attack with any generality. However, while research has paid little attention to data cleaning, industry has been forced to deal with this on a regular basis. This issue of the Bulletin addresses this long-standing and important problem. Sunita Sarawagi has herself worked in this important area, and has succeeded in soliciting papers from a mix of academia and industry, with papers from Europe and Asia, as well as the US. Thus the issue provides a very broad perspective on this important subject. Sunita has done a fine job as editor of the issue, and I want to thank her for her hard work.