The increasing interest in process engineering and application integration has resulted in the appearance of various new process modelling languages. Understanding and comparing such languages has therefore become a major problem in information systems research and development. We suggest a framework to solve this problem involving several instruments: a general process meta-model with a table, an analysis of the event concept, and a classification of concepts according to the interrogative pronouns: what, how, why, who, when, and where. This framework can be used for several purposes, such as translating between languages or verifying that relevant organisational aspects have been captured. To validate the framework, three different process modelling languages have been compared: Business Modelling Language (BML), Event-driven Process Chains (EPC) and UML State Diagrams.