This paper empirically investigates the advantages and limitations of modeling languages by specifying the multi-lift system as a non-trivial case study. The multi-lift system is a suitable test bed to demonstrate the expressive power of modeling languages in specifying such a concurrent, reactive, and complex system. English, UML, and Object-Z have been chosen, respectively, as informal, semi-formal, and formal modeling languages to specify the software requirements of the multi-lift system. These modeling languages are then compared and evaluated based on their likelihood to produce a specification with some defined characteristics. The conclusion is that informal languages such as English cannot be used to produce software models, because they are prone to ambiguity. Each of the formal and semi-formal languages has some unique advantages and limitations. Semi-formal models should be supplemented with formal ones to produce high quality software.

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