The Damage Rating Index (DRI) was developed in the 1990s as a petrographic examination-based tool to assist in characterizing the amount of damage present in concrete caused by the effects of alkali-silica reaction (ASR), specifically in dams. The DRI provides a readily understood numeric index of the amount of damage in concrete on a scale in which low DRI values indicate little or negligible effects, whereas higher DRI values correspond with a greater number of effects, typically also associated with damage of increasing concern. Details of the approach that is used in the DRI analysis of ASR-affected concrete are provided, including a discussion of the relative merits of each of the characteristics that produce a DRI value for concrete. Different emphases as well as different methodologies, when applied, have been observed to result in significant variability of the results. The DRI can also indicate the likelihood of further expansion, as well as the degree of such expansion. These inputs can support or inform an assessment of the overall service life of individual concrete elements when compared with other concrete of similar composition. The paper examined methods of this application of the DRI procedure and provided examples from projects.