SESAMME (Socio-Ecological App for Mental Model Elicitation) has been designed as a user-friendly tool for developing participatory 'rich pictures' for a specified socio-ecological problem. Using a 'drag and drop' approach, the User can draw upon a library of icons that represent resources (e.g. fish), activities (e.g. farming), pressures (e.g. population growth) and place these on a map of any location in the world. The causal relationship between any two icons can then be specified by drawing interactions between them. Further features of the socio-ecological system such as past and future trends of an icon, the current state of an icon and the nature of the relationship between two connected icons can also be used. SESAMME is designed to be intuitive and easily used, especially in participatory group model building environments.