The adaptation, specially by means of a simplification process, of modeling languages is a common practice due to the overwhelming complexity of most standard languages (like UML or BPMN), not needed for typical usage scenarios while at the same time companies don't want to go to the extremes of defining a brand new domain specific language. Unfortunately, there is a lack of examples of such simplification experiences that can be used as a reference for future projects. In this paper we report on a field study aimed at the simplification of a business process modeling language (namely, BPMN) for making it suitable to end users. Our simplification process relies on a set of steps that encompass the selection of the language elements to simplify, generation of a set of language variants for them, measurement of effectiveness of the variants through user modeling sessions and extraction of quantitative and qualitative data for guiding the selection of the best language refinement. We describe the experimental setting, the output of the various steps of the analysis, and the results we obtained from users. Finally, we conclude with an outlook towards the generalization of the approach and consolidation of a language simplification method.