Medieval historical miscellanies have traditionally been seen as repositories of random historical information. This essay examines how the miscellany form makes possible a distinct mode of cultural memory construction, the piecing together of anecdotes gathered from oral and written sources to create a composite, multifaceted picture of the past, or "mosaic memory." Using as examples four monothematic post-An Lushan rebellion collections devoted to the memory of the Kaiyuan-Tianbao era (713-756), we may see how compilers created idiosyncratic versions of mosaic memory as a result of their personal motives and cultural positions. These individual versions also overlay and constitute a cumulative representation that reveals important features of mosaic memory as a communal discourse. The layered formation of mosaic memory helps to shed light on how the cultural memory of the Kaiyuan-Tianbao era took shape in the mid- and late-Tang periods and how medieval historical miscellanies functioned as an important site of cultural production.