Abstract. In component-based development, the correctness of a system depends on the correctness of the individual components and on their interactions. Model-based testing is a way of checking the correctness of a component by means of executing test cases that are systematically generated from a model of the component. This model should include the behaviour of how the component can be invoked, as well as how the component itself invokes other components. In many situations, however, only a model that specifies how others can use the component, is available. In this paper we present an approach for model-based testing of components where only these available models are used. Test cases for testing whether a component correctly reacts to invocations are generated from this model, whereas the test cases for testing whether a component correctly invokes other components, are generated from the models of these other components. A formal elaboration is given in the realm of labelled trans...