The 11th International Conference on Reliable Software Technologies, Ada- Europe 2006, took place in Porto, Portugal, June 5-9, 2006. It was as usual sponsored by Ada-Europe, the European federation of national Ada societies, in cooperation with ACM SIGAda. It was organized by members of the School of Engineering of the Polytechnic Institute of Porto, in collaboration with several colleagues from di?erent institutions in Europe. Following the usual style, the conference included a three-day technical p- gram, during which the papers contained in these proceedings were presented, bracketed by...