Now That's What I Call Music! 55 is the 55th edition of the Now! series in the United States, and the compilation was released on August 7, 2015. It features 21 tracks including the Billboard Hot 100 number-one hit, "Cheerleader" by OMI.

Now 55 debuted at number three on the Billboard 200 albums chart with 76,000 albums sold in its first week of release.