The term "sustainability" has entered the lexicon of many academic disciplines and fields of professional practice, but to date does not appear to have been seriously consid­ ered within the systems community unless, perhaps, under other guises. Within the wider community there is no consensus around what sustainability means with some authors identifying 70 to 100 definitions of the term. Some see sustainability as the precise and quantifiable outcomes of biological systems whilst others see it in terms of processes rele­ vant to personal and organizational change with the potential to effect changes in our relationships with out environments. Internationally it has been increasingly used in relation to the term "sustainable development"—a term popularised by the Brundland Commis­ of definitions sion's report in 1987 entitled "Our Common Future. " Despite this diversity and polarised perception on its utility, unlike many other popular terms, it has not had its time and subsided quietly from our language. It is therefore timely for the systems com­ munity to explore the relationship between systems and sustainability in a range of con­ texts. Participants in this, the 5th International Conference of the United Kingdom Systems Society (UKSS), have been invited to reflect critically on the contribution of systems thinking and action to sustainability-to the sustainability of personal relationships, the organizations in which live and work, and our "natural" environment.