Over-the-Rhine (OTR) in Cincinnati, Ohio is among the largest and most significant historic districts in the U.S., designated as a historic district in both the National Register of Historic Places and locally. Growing interest in revitalizing the neighborhood has spurred historic rehabilitation and investment in new construction (i.e., “infill”) on the neighborhood’s many vacant lots -- especially since the early 2000s. While OTR is significant for its Italianate architecture and its remarkably cohesive character, infill is often of a different character, threatening the integrity and identity of the neighborhood’s setting. Owing to decades of policy decisions and a deeply ingrained philosophy that infill must stand in contrast to its historic neighbors, the character of OTR is being eroded by new construction and may be destroyed if the trend continues. This thesis analyzes both the policy and theory that have contributed to this phenomenon, concluding that the appropriate approach to infill in OTR is one that favors continuity of architectural character over contrast with historic fabric. An objective rubric for appropriateness of infill in OTR is established based on empirical elements of architectural character. The rubric is applied to 29 case studies of infill projects in OTR. Five additional case studies outside of but relevant to OTR are also included to provide an external frame of reference. Based on the findings of the case studies, the thesis concludes with recommendations for how to mitigate the adverse effects of existing incompatible infill and ensure that future infill is more appropriate to the character of OTR.