This book is the primary publication for Soft Systems Methodology. In it, Peter Checkland describes the rise of systems thinking, and argues the case for the soft systems approach. The methodology is explained, and various considerations which arose through it's use explored. SSM, which has been continuously evolving over the last 25 years, is as relevant to problems in social research, management studies and intervention in social systems as it ever was. I also liked the sequel Soft Systems Methodology in Action.