This article reviews the history and types of double crown retainers, known in clinical terms as telescope crowns. It compares rigidly interlocked and resilient retainers, where the design allows for movement between the primary and secondary components of the unit. The nature of the relationship between the components determines the relationship between the removable denture, the remaining dentition, and the edentulous ridge. The resiliency or rigidity of the telescope retainers depends on the configuration of the primary and secondary components and is applied accordingly to prosthodontic requirements and clinical assessment.