Each year the Safety-critical Systems Symposium brings together practitioners and researchers in a quest to inculcate a higher degree of safety engineering into the development and operation of critical software-based systems. On this, the Symposium's seventh occasion, it explores recent work and experience which lead us further 'towards system safety'. This book of the Proceedings covers the entire event. The first paper is the course text of a tutorial run on the first day of the Symposium, included here to provide readers with a coverage of the entire event. The next fourteen papers were presented, on the second and third days, in six sessions: Safety Cases, Systems Engineering, Safety Analysis and Safety Integrity, Tools for Software Safety, Solving Safety Problems, and Qllestions and Competences. Eight of the fourteen papers were authored in industry, four in universities, and two in other research establishments. Four of them report on work outside the UK: in France, Germany, Norway and Brazil. There are three papers on safety cases, each taking a different perspective. Skogstad from Norway and Boyce and Hamilton of GEC-Marconi both report on experience in the field, the former in attempting to apply European norms to project documentation and the latter in attempting to build up a retrospective safety case. The third paper, by Goodman, takes a more philosophical stance, examining the lack of useful measurement in safety assurance.