ACRE is an Agro-eConomic model for agricultural pRoduction on rEgional level. Based on an extension of Positive Mathematical Programming (PMP) this model was developed as a decision tool for politics with respect to questions of global change scenarios. The validity of the theoretical approach as well as the algorithms has been tested by calculations with empirical data. Currently, ACRE is applied in large interdisciplinary projects. This paper introduces the development of ACRE, from the theoretical framework to testing its validity and current application.