This volume contains the papers presented at the Third International Conference on Object Oriented Information Systems (00lS'96) which was held at South Bank University, London. The keynote addresses, by Professor Colette Roland and Mr Ian Graham, are also included. The acceptance rate for papers was around 47%. The papers for the Industry Day were invited papers. The keynote paper by Professor Roland analyses the challenges in object modelling, particularly the impact of requirements engineering for conceptual modelling. She suggests innovative research perspectives to enhance and extend object oriented approaches in order to deal with the emerging area of requirements engineering. The keynote paper presented by Mr. Graham focuses on the problems and solutions for adopting use cases. In his paper, Graham illustrates the theoretical issues and practical problems of use cases, and highlights them using examples. The papers included in this volume cover different aspects of object modelling, object oriented software development, object databases, and interoperability. In the modelling session, Ram, et al. outline an extended object model to tackle the problems of capturing complex requirements of office information systems. Simons' paper concentrates on core object modelling concepts and presents a mathematical theory of class.