Software engineering environments are intended to provide a cohesive and integrated set of tools to support the process of software engineering with much current research into environment design focussed on maximising the degree to which these tools can be integrated. This paper describes the architecture of a prototype environment which attempts to achieve a high degree of integration using techniques drawn from artificial intelligence, office automation and object-oriented programming. This environment is implemented as a federation of intelligent, co-operating agents which communicate, with each other and with users, by message passing. This paper is particularly concerned with user interface integration including the mechanisms employed to permit inter-agent and agent-user communications.