An object-oriented, computer-based system for developing simulation models is provided. The system comprises one or more base objects and one or more graphical processes, wherein new objects are created from base objects by a user by assigning one or more graphical processes to the base object(s). New objects are created without the need for methods or computer programming. A model is built by creating objects that represent the physical components of the system being modeled into the model, and then running the model.