A sign assembly includes a substantially rigid framework such as a rectangular or other shaped frame, and a flexible display sheet, typically of cloth or fabric material. The display sheet wraps around an outer portion of the framework and enters a channel, where it is retained at a flexible retainer element disposed in the channel. Optionally, the flexible retainer element may be a strip of resilient sheet material defining one or more slit or slot patterns and/or openings that are configured to releasably engage portions of the display sheet. A cover element may be used to cover the channel and to present a finished appearance along the outside portion of the framework.