On the basis of Sanskrit and Greek, we may conclude that the Proto-Indo-European verb did not have a conjugational system. Many verbs, for example, only had either a present or an aorist system. Sanskrit and Greek show a continuation of the Proto-Indo-European system, while Latin, for example, developed a conjugational system. For Sanskrit, a description was offered by D. Whitney in 1885. In later Greek, the old situation is reflected in the use of suppletion. A complete inventory of the Greek material, however, has never been generated. This study presents for the first time a complete description of the possibilities in inflection (the "individual verbal system") of all of the verbs that Greek inherited from Proto-Indo-European, up to the fifth century (and, in some cases, later). In the second part of the study, the core of each individual verbal system is arranged according to present class, aorist class, and their combinations. Contents: Abbreviations Introduction Chapter One: Definition of the corpus and the framework 1.1 The corpus 1.2 Verbs attested too late 1.3 Greek innovations 1.4 Onomatopoetic verbs 1.5 Verbs without a good etymology 1.6 Verbs with an Indo-European etymology 1.7 Verbs with an old root structure (ORS) 1.8 Verbs with an old individual verbal systems (OIVS) 1.9 Verbs with a less certain etymology (PO) 1.10 Framework 1.11 Heuristics Chapter Two: The individual verbal systems Chapter Three: Present - aorist combinations Chapter Four: Aorist - present combinations Chapter Five: Survey of perfects Statistics Bibliography Index