This volume contains the papers presented at the 7th International Conference on Discovery Science (DS 2004) held at the University of Padova, Padova, Italy, during 2-5 October 2004. The main objective of the discovery science (DS) conference series is to p- videanopenforumforintensivediscussionsandtheexchangeofnewinformation amongresearchersworkingintheareaofdiscoveryscience. Ithasbecomeagood custom over the years that the DS conference is held in parallel with the Int- national Conference on Algorithmic Learning Theory (ALT). This co-location has been valuable for the DS conference in order to enjoy synergy between c- ferences devoted to the same objective of computational discovery but from di?erent aspects. Continuing the good tradition, DS 2004 was co-located with the 15th ALT conference (ALT 2004) and was followed by the 11th Symposium on String Processing and Information Retrieval (SPIRE 2004). The agglome- tion of the three international conferences together with the satellite meetings was called Dialogues 2004, in which we enjoyed fruitful interaction among - searchers and practitioners working in various ?elds of computational discovery. The proceedings of ALT 2004 and SPIRE 2004 were published as volume 3244 of the LNAI series and volume 3246 of the LNCS series, respectively. The DS conference series has been supervised by the international ste- ing committee chaired by Hiroshi Motoda (Osaka University, Japan). The other members are Alberto Apostolico (University of Padova, Italy and Purdue U- versity, USA), Setsuo Arikawa (Kyushu University, Japan), Achim Ho?mann (UNSW, Australia), Klaus P. Jantke (DFKI, Germany), Masahiko Sato (- oto University, Japan), Ayumi Shinohara (Kyushu University, Japan), Carl H.