This paper presents a Petri net approach to designing supervisory control logic for integrated manufacturing systems and its application to design of the Laserlite Workstation Control System. The work has complemented a methodology which is beign currently developed using the Manufacturing Information Systems Toolkit for Building Integrated Control Systems (MISTIC) at AT&T Engineering Research Center  in the several aspects. First, explicit representation of supervisory control logic is obtained by using Petri nets. Thus concurrency, choices, and precedence relations can be graphically visualized. Second, mathematical analysis can be conducted for both qualitative and quantitative properties of the control systems. Inconsistency errors and deadlock situations can be detected. The temporal properties can be derived by incorporating timing information into the net representation if needed. Third, based on the net representation of the system, control code in C or C++ can be systematically derived. Fourth, related control system components and their description using MISTIC are certainly useful in specifying a practical implementation. Finally, new schemes can be exploited by modifying the net structure or changing the initial condition. Future research is finally discussed for control software development in the context of computer integrated manufacturing.