"Don't Let Me Down" is a song by American production duo The Chainsmokers. The song features the vocals of American singer Daya, and was released on February 5, 2016, through Disruptor Records and Columbia Records. The song was written by Andrew Taggart, Emily Warren and Scott Harris. It was released on March 22, 2016, as the radio single follow-up to "Roses".

"Don't Let Me Down" became both The Chainsmokers' and Daya's first top five single on the US Billboard Hot 100, peaking at number three. It also became The Chainsmokers' second consecutive top 10 entry after "Roses", which peaked at number six. It reached the top 10 in several countries, including Australia, Austria, Canada, Germany, New Zealand, Sweden, and the United Kingdom. A set of remixes for the song, was released on April 15, 2016. A music video for the song was released on April 29, 2016, with appearances from The Chainsmokers and Daya.

The song won a Grammy Award for Best Dance Recording.

In an interview, Taggart stated that he first created the drop during a flight. The duo later added a "big, echoey guitar sound" to the song, inspired by the bands the xx and Explosions in the Sky, by using a Fender electric guitar and a software plugin. Emily Warren and Scott Harris convened with the duo to create the melody and lyrics. However, the vocalist was not chosen until Taggart heard Daya's "Hide Away", after which the duo enlisted her to record the vocals in the studio.

The key of the song was originally a step lower, but the duo changed it in order to better accommodate Daya's range. The third drop, which includes the saxophone, was created later in the process. The song has a double-time tempo of 80 beats per minute and a key of G♯ minor. "Don't Let Me Down" follows a chord progression of E – B – F♯ – G♯m, and Daya's vocals span from G♯₃ to C♯₅.

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