Abstract This paper x-rays the use of Critical Path Method-Project Evaluation Review Technique (CPM/PERT) cost function and Earned value system in monitoring and controlling civil and building engineering projects. The system culminates in the progressive generation of the CPI-SPI graphical contour which guides the project team in tracking projects. It is a simple step-by-step approach towards ensuring that what was executed is critically evaluated in the light of planned activities and providing indicators to project performance and an early warning system for corrective measures. Using the graphical explanation of the project under review, it was observed that a cost saving of 1.5% (N262, 488.13) from the scheduled cost of N21, 962,448.13 and the project was completed earlier than the scheduled period of 450 working days by approximately 15 days representing a savings of 3.33%. This implies that the use of CPI-SPI in monitoring and controlling construction projects is very important.