This volume presents a collection of papers dealing with the semantics, syntax and morphology of perfect constructions in several languages (e.g. Arabic, English, Bulgarian, German, Greek, Italian, and Russian). The volume has its origin in two workshops, one on the Perfect organized by the University of Thessaloniki in May 2000, and one on Participles organized by the University of Tübingen in April 2001. However, the book is independently structured and features a different set of contributors than did those events. 1 The papers present the state of the art in current research on Perfect constructions. Although the approaches differ in their details, a general consensus emerges concerning structural aspects of tense/aspect/aktionsart distinctions (T/A/A). In our introduction we discuss these aspects in detail. Furthermore, we introduce the temporal meaning components that the contributors use in their analysis. We address issues that relate to the interpretation of simple tenses, the perfect, viewpoint aspect, aktionsarten, aspectual and durative adverbials. As will become evident, the amazing complexity of perfect constructions relates to the ways the morpho-syntax of such constructions expresses their semantics. 2. Perfect constructions Perfect constructions interact with Tense (present/past), with viewpoint aspect, with aktionsarten and with temporal adverbs of different sorts. Any analysis of these constructions has to take into account all these factors, which are often only partly understood. There are two main perfect constructions that the contributions to this volume focus on: one expressed by the have-perfect and one by the beperfect. Note that what we call here have and be-perfects do not strictly correspond to the phenomenon of auxiliary selection. Rather with beperfects we describe adjectival passives, which can have readings that relate to uses of the perfect (see e.g. Anagnostopoulou's contribution). We discuss these in turn.