The last ten years have seen a gradual fragmentation of the Automated Reas- ing community into various disparate groups, each with its own conference: the Conference on Automated Reasoning (CADE), the International Workshop on First-Order Theorem Proving (FTP), and the International Conference on - tomated Reasoning with Analytic Tableau and Related Methods (TABLEAUX) to name three. During 1999, various members of these three communities d- cussed the idea of holding a joint conference in 2001 to bring our communities togetheragain.Theplanwastoholdaone-o?conferencefor2001,toberepeated ifitprovedasuccess.Thisvolumecontainsthepaperspresentedattheresulting event:the?rstInternationalJointConferenceonAutomatedReasoning(IJCAR 2001), held in Siena, Italy, from June 18-23, 2001. We received 88 research papers and 24 systems descriptions as submissions. Each submission was fully refereed by at least three peers who were asked to writeareportonthequalityofthesubmissions.Thesereportswereaccessibleto membersoftheprogrammecommitteeviaaweb-basedsystemspeciallydesigned for electronic discussions. As a result we accepted 37 research papers and 19 system descriptions, which make up these proceedings. In addition, this volume contains full papers or extended abstracts from the ?ve invited speakers. Tenone-dayworkshopsandfourtutorialswereheldduringIJCAR2001.The automatedtheoremprovingsystemcompetition(CASC)wasorganizedbyGeo? Sutcli?e to evaluate the performance of sound, fully automatic, classical, ?r- order automated theorem proving systems. The third Workshop on Inference in Computational Semantics (ICoS-3) and the 9th Symposium on the Integration of Symbolic Computation and Mechanized Reasoning (CALCULEMUS-2001) were co-located with IJCAR 2001, and held their own associated workshops and produced their own separate proceedings.