Recent analyses of ontology engineering efforts showed that it is not only novices which are commonly faced with com- prehension problems or misconceptions of modeling conse- quences. A better understanding can be fundamentally sup- ported by on-demand explanations of subsumption, the core inference service of ontology reasoning systems. In this pa- per we describe ongoing work towards a systems for explain- ing subsumption for a significant fraction of the Description Logic underlying OWL Lite. Our explainer uses a tableau- based approach to generate step by step quasi-natural lan- guage explanations. We also comment on related work and discuss future explaining features.