Based on the Net.ObjectDays tradition of bringing together researchers from academia and industry on the one hand and system architects, developers, and users fromindustry andadministrationon the other hand, this year sconference took an international research perspective, so that we see the?rst volume of Net.ObjectDays main conference proceedings published in the Springer Lecture Notes in Computer Science series. This volume consists of 16 papers carefully selected in a rigorous reviewing process by an international program committee; to provide a concise overview, these papers are brie'y described. In the Languages and Models session, Beate Ritterbach proposes a new l- guage element for object-oriented programming languages that supports ar- trary value types. In her contribution Support for Value Types in an Object- OrientedProgramming Language shedescribesthecorrespondingkeywords, s- tax, and consistency checks, thereby giving an impression of the look and feel of value types from an application programmer s perspective. Walter Binder and Jarle Hulaas look at portable CPU accounting and control in Java, which is based on program transformation techniques. In their paper Self-accounting as Principle for Portable CPU Control in Java periodically the threads of an application component aggregate the information of their respective CPU c- sumption within a shared account; scheduling functions make sure applications do not exceed their allowed CPU share."