This book contains the refereed proceedings of the 12th International Conference on Business Information Systems, BIS 2009, held in Poznan, Poland, in april 2009. The 22 revised full papers were carefully reviewed and selected from 74 submissions. Following the theme of the conference "Information Systems for Agile Organizations", the contributions illustrate recent tendencies in making organizations more adaptive and responsive with respect to changing external conditions. They are grouped in sections on ontologies in organizations, ontologies and security, Web search, process modelling, process analysis and mining, service-oriented architecture, and enterprise resource planning.