This book constitutes the thoroughly refereed postproceedings of the Second International Workshop on Databases, Information Systems, and Peer-to-Peer Computing, DBISP2P 2004, held in Toronto, Canada in August 2004 in conjunction with VLDB 2004.The 14 revised full papers presented together with an invited keynote paper were carefully selected during two rounds of reviewing and improvement. The papers are organized in topical sections on query routing and processing, similarity search in P2P networks, adaptive P2P networks, and information sharing and optimization.