"Reliable Software Technologies - Ada-Europe 2007" is a technical book that documents the proceedings of the 12th International Conference on Reliable Software Technologies, which took place from June 25 to 29, 2007, in Geneva. This conference, organized by Ada-Europe in collaboration with ACM SIGAda, provides a platform for the exchange of ideas and advancements in the development of reliable software. The book includes contributions from experts from various European institutions and highlights both industrial techniques and academic disciplines in the field of software reliability. The conference has a long tradition dating back to 1996 and promotes dialogue between academia and industry to enhance the quality and reliability of software solutions. The collected works in this volume are a valuable contribution to the advancement of software technologies and offer insights into current trends and challenges in this field.