Abstract: As has been shown in previous work, the separation of concerns provided by reflective architectures is of high interest for the development of dependable systems. Beyond this initial interest, the use of this technology remains questionable due to the lack of work reporting on validation aspects. This paper defines an incremental strategy for testing the cornerstone of the reflective architectures that we consider, i.e., the MetaObject Protocol (MOP). The approach is aimed at reducing the testing effort by promoting a gradual increment of the observability and controllability of the MOP under test. This strategy enables reflective mechanisms that have already been tested to be reused for verifying the remaining ones. A different testing level is associated with each reflective mechanism defined in the MOP. For each testing level, we characterize the test objectives and the required test environment. The feasibility of the approach is exemplified on a real MOP implemented using OpenC++ and extracted from the FRIENDS architecture devoted to the implementation of CORBA dependable systems. First test experiments were very useful since they revealed some implementation errors.