This special issue on Data Resources, Evaluation, and Dialogue Interaction is based on five thoroughly revised and extended papers from the sixth SIGdial Workshop held in Lisbon, Portugal, in September 2005. SIGdial is a special interest group on discourse and dialogue whose parent organisations are the Association for Computational Linguistics (ACL) and the International Speech Communication Association (ISCA). SIGdial workshops accommodate a broad range of topics related to discourse and dialogue. Among these topics are data resources, evaluation, and dialogue interaction. The papers selected for this special issue have in common that they all deal with aspects of these topics and each paper has its focus on at least one of them.