The effect of service-learning on college and university students has attracted considerable scholarly attention in the last decade. However, few attempts to replicate studies are conducted. The purpose of the research reported in this article is threefold: (1) to assess the reliability of a modified version of Kelly, Chase, and Tucker's (1979) taxonomy to discriminate accurately between sub-categories of replication in studies of service-learning outcomes; (2) to determine the extent of replications in the service-learning outcomes literature; and (3) to make recommendations based on the study's results. The research sample consists of data-based articles published in peer-reviewed journals between[space] 1993 and 2004. The taxonomy's ability to discriminate [between] types of replications yields an inter-rater reliability of 88 percent. The results indicated that 31 (70.4 percent) of the studies were classified as either operational or constructive replications. Many of the studies were “within-study” replications, meaning that researchers are replicating their own research. Several recommendations for improving the quality of service-learning outcomes research are proposed.