The authors, collaborating from several public health institutes, present the methodology, results, and lessons learned from a multistate needs assessment of local and state public health and safety officials regarding their familiarity and use of formal computer modeling for preparedness activities. The study was undertaken to provide information to the newly formed Preparedness Modeling Unit within the Centers for Disease Control and Prevention. The focus was on the use of sophisticated mathematical models associated with three public health threats: pandemic influenza, radiologic release, and severe heat waves. The use of computer modeling and scenario-based analyses can be used to better frame problems and opportunities, integrate data sources, expect outcomes, and improve multistakeholder decision making. The results of the eight state needs assessment demonstrated that preparedness officials are familiar with models and would use computer modeling as a tool, along with other tools and general experiences, depending upon the perceived quality and validity of the model and the assumptions, as well as the applicability, of the model to their particular setting and population. More needs to be done to improve awareness and dissemination of available models and share best practices in both knowledge and use of models. Use of preparedness modeling would enhance the planning for vulnerable and at-risk populations, all-hazard emergencies and infectious disease containment strategies, as well as for response functions including evacuation, sheltering, quarantine, and distribution of medications and supplies.