The background to IDA 2010, the 9th International Symposium on Intelligent DataAnalysis(IDA), is ratherunusual. Previously, thesymposiawereheldbi- nially at European venues. Over this time, the IDA Symposium had established an identity, a dedicated group of Program Committee members, and a regular audience. However, this success had come at a cost to the original ambitions for the symposium - concerned with interfacing AI, statistics and computer science for important and di?cult real-world data analysis problems - being comp- mised in favor of more standard data mining content. IDA 2010 was organized explicitly to re-align the IDA Symposia series with a set of objectives evolved from the original ambitions. This should be construed not as a criticism of r- tine data mining research but rather as an admission that the IDA symposium had taken the path of least resistance with respect to the call for papers and the reviewing process. This is the proceedings volume of IDA 2010, a special event held only a year after the eighth symposium in an attempt to revitalize the area of IDA. There were two major changes compared to previous symposia. First, the Call for - pers (CfP) was completely rewritten, placing great emphasis on algorithms and systems thatsupportmodelling andanalysisofcomplex real-worldsystems. - reover, the CfP explicitly discouraged submissions that might be characterized as "incrementaladvances indata mining algorithms. "Second, the reviewing- chanism was extended to include a "senior ProgrammeCommittee," in response to perceived shortcomings in the existing reviewing process.