Mr.Mr. is the fourth extended play (EP) by South Korean girl group Girls' Generation. The EP consists of six tracks and it incorporates electropop and R&B-pop music genres. It was released for digital download by SM Entertainment and KT Music on February 24, 2014.  it topped the Gaon Monthly Album Chart with sales of 70,295 copies. It was placed at number 47 on the Gaon Monthly Album Chart of April with a further 1,125 units sold.Overall, Mr.Mr. was the fifth highest-selling physical album and the best-selling album by a girl group of 2014 in South Korea with total sales figures of 163,209 copies. Mr.Mr. debuted at number 110 on the US Billboard 200 chart, selling 3,000 copies in its first week. By doing so, the EP became Girls' Generation's highest-charting release on the Billboard 200 following subgroup TTS's Twinkle, which charted at number 126 in 2012. Mr.Mr. also peaked at number three on the World Albums, and number 23 on the Independent Albums charts. In Japan, it peaked at number eleven on the Oricon Albums Chart.

The song "Soul" (Korean version) was co-written and produced by Dsign Music.