Description:This book constitutes the refereed proceedings of the Second International Conference on Rough Sets and Knowledge Technology, RSKT 2007, held in Toronto, Canada in May 2007 in conjunction with the 11th International Conference on Rough Sets, Fuzzy Sets, Data Mining, and Granular Computing, RSFDGrC 2007, both as part of the Joint Rough Set Symposium, JRS 2007.The 67 revised full papers presented together with three invited papers were carefully reviewed and selected from a total of 319 general submissions to the JRS 2007 symposium. The papers are organized in topical sections on rough set foundations, multiple criteria decision analysis, biometrics, kansei engineering, autonomy-oriented computing, soft computing in bioinformatics, ubiquitous computing and networking, rough set algorithms, knowledge representation and reasoning, genetic algorithms, and rough set applications.