MuTACLP: A language for declarative GIS analysis. This paper proposes an integration between Geographical Information System (GIS) technology and constraint logic programming in order to supply the user with a declarative language that supports and improves GIS analysis. We present the language MUTACLP, where spatio-temporal and thematic information can be represented in a uniform way, and the features of constraint logic programming, such as recursion and constraint handling, can be exploited to perform sophisticated spatio-temporal reasoning. This unifying language seems also promising to address the key problem of interoperability among different GISs.