The refereed proceedings of the International Conference on Web Engineering, ICWE 2003, held in Oviedo, Spain in July 2003. The 25 revised full papers and 73 short papers presented together with 2 invited papers were carefully reviewed and selected from 190 submissions. The papers are organized in topical sections on agents on the Web, e-commerce, e-learning, human-computer interaction, languages and tools, mobility and the Web, multimedia techniques and telecommunications, security, Web quality and testing, semantic Web, and Web applications development.