This book constitutes the refereed proceedings of the 34th International Colloquium on Automata, Languages and Programming, ICALP 2007, held in Wroclaw, Poland in July 2007.

The 76 revised full papers presented together with 4 invited lectures were carefully reviewed and selected from 242 submissions. The papers are grouped in three major tracks on algorithms, automata, complexity and games, on logic, semantics, and theory of programming, and on security and cryptography foundations.