The objective of this paper to develop an integrated method for evaluating creep-fatigue damage accumulation and crack growth at critical fossil plant steam piping locations using existing instrumentation and available plant operating data. The resulting methodology permits the cumulative damage and structural integrity of steam piping and other components to be monitored and tracked, based on actual plant operating cycles and temperatures. The methodology has been implemented in a software system called Creep-FatiguePro. A prototype system has been installed and tested for a limited number of locations at the Pacific Gas and Electric Company's Contra Costa Power Plant. The results of this pilot plant demonstration show the feasibility of such an on-line monitoring system. Based upon these results, such a system is felt to offer significant cost-benefit advantages in optimizing plant maintenance and life assessment activities.