The study endeavors a detailed and systematic classification of linguistic simultaneity expressions. Further, it aims at a well described survey of how simultaneity is expressed by native speakers in their own language. On the basis of real production data the book answers the questions of how native speakers express temporal simultaneity in general, and how learners at different levels of proficiency deal with this situation under experimental test conditions. Furthermore, the results of this study shed new light on our understanding of aspect in general, and on its acquisition by adult learners.