From Object Orientation to Formal Methods : Essays in Memory of Ole Johan Dahl This book is dedicated to the memory of Ole Johan Dahl who passed away in June 2002 at the age of 70 shortly after he had received together with his colleague Kristen Nygaard the ACM Alan M. Turing Award: For ideas fundamental to the emergence of object oriented programming through their design of the programming languages Simula I and Simula 67. This Festschrift opens with a short biography and a bibliography recollecting Ole Johan Dahls life and work as well as a paper he wrote entitled: The Birth of Object Orientation: the Simula Languages. The main part of the book consists of 14 scientific articles written by leading scientists who worked with Ole Johan Dahl as students or colleagues. In accordance with the scope of Ole Johan Dahls work and the books title the articles are centered around object orientation and formal methods