Models, created using different modeling techniques, usually serve different purposes and provide unique insights. While each modeling technique might be capable of answering specific questions, complex problems require multiple models interoperating to complement/supplement each other; we call this Multi-Modeling. To address the syntactic and semantic challenges of this multi-modeling approach for solving complex problems, a systematic methodology for developing multi-modeling workflows is presented. The approach is domain specific: Identification of the domain and the supporting modeling techniques is the first step. Then a Domain Specific Multi-Modeling Workflow Language (DSMWL), supported by a Domain Ontology, is developed and then used to construct workflows that capture interoperations between various models. The domain ontology provides semantic guidance to effect valid model interoperation. The approach is illustrated using a case study from the Drug Interdiction and Intelligence domain. The Joint Inter-Agency Task Force (JIATF)-South, an agency well known for interagency cooperation and intelligence fusion, receives large amounts of disparate data regarding drug smuggling efforts. Analysis of such data using various modeling techniques is essential in identifying best Courses of Action (COAs). The proposed methodology is applied to the Drug Interdiction domain by performing domain analysis, developing a Domain Specific Multi-Modeling Workflow Language (DSMWL) and a Domain Ontology, and then using the DSMWL and the Domain Ontology to create workflows of model interoperations involving Social Networks, Timed Influence Nets, and Geospatial models. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]