Process management incorporates a plethora of models, which are expressed in different languages for different layers of abstraction. A holistic process modeling environment must provide means for dealing with three types of modeling constraints. First, it must ensure a model's correctness. Second, a modeling environment must account for compliance of models with respect to models on higher layers of abstraction. Third, consistency of different models of the same language layer should be supported. In this paper, we exemplify these three constraint types and discuss how they can be enforced in a holistic modeling environment.