This volume includes extended and revised versions of the best papers of the 1st International Conference on Simulation and Modeling Methodologies, Technologies and Applications (SIMULTECH-2011). The purpose of this conference is to bring together researchers, engineers, applied mathematicians and practitioners interested in the advances and applications in the field of system simulation. It has four simultaneous tracks, covering on one side domain independent methodologies and technologies and on the other side practical work developed in specific application areas. The specific topics listed under each of these tracks highlight the interest of this conference in aspects related to computing, including Conceptual Modeling, Agent Based Modeling and Simulation, Interoperability, Ontologies, Knowledge Based Decision Support, Petri Nets, Business Process Modeling and Simulation, amongst others.