Fieldbus technology has been under development for many years and is approaching maturity. This will have widespread implications for the way in which industrial process plants are designed, operated and maintained. This paper reviews the benefits which the new generation of highly distributed process control systems promise to deliver to end users, and identifies that the introduction of this new technology carries considerable risk. It is proposed that the use of appropriate engineering tools will be an important factor in reducing the risks to acceptable levels. The principle user requirements for fieldbus engineering tools are discussed. The ACORN 1479 collaborative research project is implementing such a design toolkit which will be validated in the context of pilot applications in the Chemical and Power sectors. This paper presents the key findings of the project at its mid term including an overview of the toolkit architecture and the pilot applications.