A key to a successful programmable logic controller (PLC) computer monitoring and control system is in the effective implementation of the system. An implementation approach for the system must be developed with the project concept and is not complete until the final acceptance of the completed system. This approach is similar in both new plant constructions and existing plant upgrades. The upgrading of existing plants does however, add some additional concerns that are not present in new plant construction and must be addressed. It is the upgrade to existing plants that will be the focus of the implementation approach followed in this paper. The paper defines the elements necessary for effective implementation of PLC/computer control and monitoring systems. This process is followed through the typical project phases. These phases are broken down into: conceptual design, detail design, final design, project bidding, system fabrication, software development, system installation, system startup, owner training, and owner acceptance.