HCI 2009 Celebrating People and Technology are the proceedings of the 23rd annual conference of Interaction, a specialist group of BCS. The conference took place at Churchill College Cambridge, from 1-5 September 2009. Topics addressed include new technology designs with potential for economic or social benefit, original and innovative interactive technologies, advances toward new ways of thinking through theories or models, tools offering understanding and evaluation of interaction design, and novel engagements with technology users or beneficiaries.