This report begins with an overview of important factors controlling the service life of concrete@ including past and current design of structures; concrete materials issues; field practices involved with placing@ consolidating@ and curing of concrete; and in-service stresses induced by degradation processes and mechanical loads. Methodologies used to evaluate the structural condition of concrete structures and the condition and properties of in-service concrete materials are presented. Methods are reviewed for predicting the service life of concrete@ including comparative methods@ use of accelerated aging (degradation) tests@ application of mathematical modeling and simulation@ and application of reliability and stochastic concepts. This is followed by a discussion of relationships between economics and the life of structures@ such as when it is more economical to replace a structure than to repair or rehabilitate. Examples are described in which service life prediction techniques are applicable to concrete structures or structural components. Finally@ needed developments to improve the reliability of service life predictions are presented.