This book discusses and summarizes the revived interest in reality issues (ontology) within accounting, economics, and the information sciences, with a view to informing scholars from these different disciplines about each other's endeavours in ontological research. Even more importantly, the book aims at familiarizing scholars from various disciplines with an evolutionary approach for examining questions about reality in the social sciences. The book is based on a partly pluralistic approach that assures unity in diversity. Unity, because all existence arises from physical reality; diversity, because emergent properties create biological and social realities that cannot be reduced to physical phenomena. Hence, the book recognizes not only concrete but also abstract entities. It shows, however, that the actualization of these abstract entities requires objectification and concrete manifestation. This pluralistic approach is central to this book. It also is a challenge to those who reject abstract entities as socially real, as well as to those who defend a non-realist position. The major task of this book is to explore proposals towards a uniform ontological basis. This uniform and universal presentation extends beyond traditional ontology (asking 'what is real?') to such questions as 'on which reality level is something real?' and 'in which (temporal and modal) way is it real?'. Such an extended analysis) is relevant to accountants, economists, information scientists, other social scientists as well as philosophers.