The introduction of the long-playing record in 1948 was the most aesthetically significant technological change in the century of the recorded music disc. The new format challenged record producers and recording artists of the 1950s to group sets of songs into marketable wholes and led to a first generation of concept albums that predate more celebrated examples by rock bands from the 1960s. Two strategies used to unify concept albums in the 1950s stand out. The first brought together performers unlikely to collaborate in the world of live music making. The second strategy featured well-known singers in songwriter-or performer-centered albums of songs from the 1920s, 1930s, and 1940s recorded in contemporary musical styles. Recording artists discussed include Fred Astaire, Ella Fitzgerald, and Rosemary Clooney, among others.