This book constitutes the refereed proceedings of UNISCON 2008 held in Klagenfurt, Austria, during April 22-25, 2008. UNISCON combines the ECOMO workshop series and the ISTA conference series. The 19 papers dealing with conceptual modeling, model-driven software development and information systems applications represent a 30% selection from the original set of submissions. They are completed by two keynote lectures and 35 papers from internationally renowned researchers, invited in honor of Heinrich C. Mayr, whose 60th birthday is also celebrated at this event, that he originally created.