There is a growing need in a range of social, environmental, and policy challenges for a richer more nuanced, yet actionable and participatory understanding of the world. Complexity science and systems thinking offer us hope in meeting this need, but in the past have often only offered either: (i) highly technical 'black box' modelling, (ii) appealing metaphors and language which don't directly lead to action, or (iii) overwhelming and paralyzing complexity. Systems Mapping is a front runner in meeting this need, providing a key starting point and general-purpose resource for understanding complex adaptive systems in practical, actionable, and participatory ways. However, there is confusion about terms and methods, an under-appreciation of the value they can bring, and a fundamental underestimation of the differences between approaches and the resulting outputs of mapping processes and analysis. This open access book explores a range of new and older systems mapping methods focused on representing causal relationships in systems. In a practical manner, it: describes the methods and considers the differences between them; describes how to use them yourself; describes how to choose between and combine them; considers the role of data, evidence, and stakeholder opinion; and describes how they can be useful in a range of policy and research settings.

Pete Barbrook-Johnson is a social scientist and complexity scientist working on a range of environmental and energy policy topics, using systems mapping, agent-based modelling, and other related approaches. He is a Departmental Research Lecturer at the University of Oxford and a member of the Centre for the Evaluation of Complexity Across the Nexus (CECAN). Alexandra S. Penn is a complexity scientist working on combining participatory methodologies and mathematical models to create tools for stakeholders to understand and 'steer' their complex human ecosystems. She is a Senior Research Fellow at the University of Surrey and a member of the Centre for the Evaluation of Complexity Across the Nexus (CECAN).