The Data Assembler (DA) is a cell based modeling environment designed to free model developers from the non-scientific aspects of software development such as file input and output, data point geo-referencing, missing data value registration and parameter input. These model independent tasks are performed internal to the Data Assembler, reducing the model code to its scientific functionality. In addition, the Data Assembler provides a means to integrate discrete cell based models written in standard C or Fortran into a versatile, graphical modeling environment.A model in the Data Assembler environment uses a small set of interface routines callable from C or Fortran to access model data and parameters. Each model is compiled as a separate executable which is accessed through the Data Assembler. During execution of the model, all data preparation tasks are performed by the Data Assembler. In addition, the Data Assembler allows for cascaded execution of models enabling modeled output to be used as input by other models. The entire chain of execution is controlled by Data Assembler.