This 2nd edition is an update of the book Wavelet Theory and Its Application to Pattern Recognition published in 2000. Three new chapters, which are research results conducted during 20012008, will be added. The book consists of two parts the first contains the basic theory of wavelet analysis and the second includes applications of wavelet theory to pattern recognition. The new book provides a bibliography of 170 references including the current state-of-the-art theory and applications of wavelet analysis to pattern recognition.