The active tectonics of the southern Aegean Sea, a region of intense shallow and intermediate depth seismicity, is studied based on well-constrained focal mechanisms. We use the focal mechanisms of 28 earthquakes (with moment magnitudes M >5.0) of the period 1977–2002 whose source parameters we determined from inversion of body waves and the focal mechanisms of 85 other earthquakes to re-examine the style of faulting and the stress field in the shallow and deeper parts of the subducting slab. Further more recent results from GPS velocity measurements and tomographic studies of the broader Aegean area were presented.