We all carry out this extensive reporting of facts and figures connected to sustainability aspects, but what we really want to know, and be able to tell, is how sustainable are we. Maybe sustainability is a mirage, which is foolish to pursue. Maybe we should rather regard sustainable development as a journey, instead of a goal Anyway there is a need for an extended sustainability theory. This work is designed to contribute with practical experience to such a theory. I also think that the managers' need for measurements of the sustainability performance is real. This thesis suggests an index for monitoring. The point is not to have an unquestionable accurate measurement, but to capture a language and a learning about sustainability impact that can be fruitful in business development towards sustainability.