Part 1. INTRODUCTION AND BACKGROUND --; Background of Software and Business Process Modeling --; Christian Schalles --; Background Theories --; Christian Schalles --; Part 2. EVALUATION FRAMEWORK AND EMPIRICAL ANALYSIS --; A Framework for Usability Evaluation of Modeling Languages (FUEML) --; Christian Schalles --; Developing a Generic Metric For Measuring Model Complexity --; Christian Schalles --; Comparing the Usability of Graphical Modeling Languages Using FUEML --; Christian Schalles --; Using Structural Equation Modeling in Usability Research --; Christian Schalles --; Impact of Metaproperties on the Usability of Graphical Modeling Languages --; Christian Schalles --; Part 3. RESUME OF THE EMPIRICAL RESULTS --; Further Processing of the Empirical Results --; Christian Schalles --; Principles for Future Development of graphical Modeling Languages --; Christian Schalles --; Part 4. CONCLUSION AND OUTLOOK --; Conclusion --; Christian Schalles --; Outlook.