Mappings between schemas are key elements in several contexts such as data exchange, data integration, peer data management systems, etc. In all these contexts, the process of designing a mapping requires the participation of a mapping designer that needs a way to validate the mapping being defined, i.e., to check whether the mapping is in fact what the designer intended. However, to date very little work has directly focused on the effective validation of schema mappings. In this paper, we present a new approach for validating schema mappings that allows the mapping designer to ask questions about the accomplishment of certain desirable properties of these mappings. We consider four properties of mappings: mapping satisfiability, mapping inference, query answerability and mapping losslessness. We reformulate these properties in terms of the problem of checking the liveliness of a derived predicate. We emphasize that this approach is independent of any particular method for liveliness checking and, to show the feasibility of our approach, we use an implementation of the CQC Method and provide some experimental results.