For the fourth time this year, in cooperation with Springer-Verlag, the Eu- peanConferenceonObject-OrientedProgramming(ECOOP)conferenceseries is gladto o?erthe object-orientedresearchcommunity the ECOOP2000Wo- shop Reader, a compendium of workshop reports, panel transcripts and poster abstractspertainingtotheECOOP2000conference,heldinCannesandSophia Antipolis from 12 to 16 June. WorkshopReports Thisyear,ECOOP2000hosted22high-qualityworkshopscoveringalargesp- trum ofhotresearchtopics.Theseworkshopswerechosenfrom38 proposalsby a workshopselectioncommittee, followinga tight peer reviewprocess. Our?rst thanks go to the members of this selection committee who worked hard during late 1999and early 2000to select the best proposals,proposepotential merges, and help those selected to enhance their ?nal material. Given the quality of the proposals,theselectionwastough;wethereforeoweaspecialthankstoallofthe submitters fortheir e?orts,whichhelped inmakingtheECOOP2000workshop programa success. Together,the22workshopsheldinconjunctionwiththeconferenceattracted more than 500 position papers, and so gathered more that 500 participants on ' the Ecole Sup' erieure en Sciences Informatiques/Institut National de Recherche enInformatiqueetenAutomatique(ESSI/INRIA)campusofSophiaAntipolis on12-13June2000.Youwill?ndinthis volumethereportsfromtheworkshop organizersof 18 of these. Following the e?orts of our preceding workshop chairs, we strived for hi- quality value-adding and open-ended workshop reports. The result, as you can judge in the following pages, is a tremendous thought-provoking snapshot of thecurrentresearchinobject-orientation,fullofpointersforfurtherexploration of the covered topics. We have to thank in a very special way our workshop organizerswho,despitetheadditionalburdenputontheirshoulders,didagreat job.