Thisvolumecontainstheproceedingsofthe26thBritishNationalConferenceon Databases (BNCOD 2009) held in July 2009 at the University of Birmingham. The theme of the conference was "Dataspace: The Final Frontier," a topic that onlyrecentlyrosetoattentionandshowspromiseofcrystallizingmanydisparate research threads into a new uni?ed vision for the future of databases. We were very grateful to have Michael Franklin of the University of Calif- nia, Berkeley, USA, and Domenico Laforenza of the Italian National Research Council (CNR) give the keynote speeches of the conference. Michael is one of the...