The objective of this book is to describe the design and implementation of a framework for the creation multi-disciplinary finite element programs. The main goals are generality, reusability, extendibility, good performance and memory efficiency. Preparing the code structure for team development to ensure the easy collaboration of experts in different fields in the development of multidisciplinary applications represents another objective of the framework. This book follows the design criteria used in implementation of the Kratos Multi-Physics framework which contains several tools for the easy implementation of finite element applications and also provides a common platform for the natural interaction of those applications. More information about Kratos can be found in: http://www.cimne.com/kratos/