This Is Acting is the seventh studio album by Australian singer and songwriter Sia. It was released on 29 January 2016 by Inertia, Monkey Puzzle and RCA Records. The album is mostly composed of songs written by Sia for other pop artists that were not included on their albums. Sia described songwriting for others as "play-acting," hence the title This Is Acting.

"Alive", the album's lead single, was released on 24 September 2015. The second single, "Cheap Thrills", was released on 11 February 2016. It reached the top 5 in a number of markets and marked Sia's first number one on the US Billboard Hot 100. A remix of the track featuring guest vocals from Sean Paul was also released. A deluxe edition of This Is Acting was released on 21 October 2016 featuring seven new tracks, including solo and Kendrick Lamar-assisted versions of the single "The Greatest". The album's fourth and final single, "Move Your Body", was released on 6 January 2017.

The album received generally positive reviews from music critics, who complimented Sia's vocals and deemed it a concept album. However, some criticized the impersonal and indirect nature of the songs. The album debuted at number one in Australia, and also reached number four on the US Billboard 200, selling 81,000 album equivalent units in its first week—of which 68,000 were from pure album sales, becoming Sia's highest first week sales in the country. To further promote the album, Sia embarked on the accompanying Nostalgic for the Present Tour in September 2016. This Is Acting was nominated for the Grammy Award for Best Pop Vocal Album.