Towrite aprefacemeansthat wehave reachedtheendofthislongway, and that in some way all the incidences and problems have been overcome. We can now say that it is really a big pleasure for us to welcome all of you to the proceedings of CAiSE 2005 which was held in Porto. CAiSE 2005 was the seventeenth in the series of International Conferences on Advanced Information Systems. Enforcing its tradition, since the late 1990s the CAiSE conferences have provided a forum for the presentation and exchange of research results and practical experiences within the ?eld of advanced infor- tionsystemsengineering.In2005, theconferencewashostedbytheFaculdadede Engenharia da Universidade do Porto, Portugal, going back to southern Europe, in particular to the Iberian peninsula, where CAiSE 1997 was held in Barcelona. The conference theme of CAiSE 2005 was "Improving Communication and Understanding - Systems and Citizens." Behind this theme, we ?nd the fact that the Internet has been changing societies and economies, and the way - stitutions and businesses operate has evolved rapidly. Most citizens are now - pected to interact directly with technology-based systems without direct human intermediation, usingdi?erentinterfaceappliances.Moreover, manyinformation systems interact with each other with limited human supervision. The Internet and its infrastructure play a critical role in this evolution, and it is of the utmost importance that semantic aspects are taken into consideration on a sound basis.