This book constitutes the refereed proceedings of the 12th East European Conference on Advances in Databases and Information Systems, ADBIS 2008, held in Pori, Finland, on September 5-9, 2008.The 22 revised papers were carefully reviewed and selected from 66 submissions. Topically, the papers span a wide spectrum of the database and information systems field: from query optimization, and transaction processing via design methods to application oriented topics like XML and data on the web.