Yotsuba&! (Japanese: よつばと!, Hepburn: Yotsuba to!) is a Japanese manga series written and illustrated by Kiyohiko Azuma, the creator of Azumanga Daioh. It has been serialized since January 2003 in the monthly magazine Dengeki Daioh by ASCII Media Works, formerly MediaWorks, and has since been collected into 16 tankōbon volumes. It depicts the everyday adventures of a young girl named Yotsuba as she learns about the world around her, guided by her adoptive father, their neighbors, and their friends. Several characters in Yotsuba&! were previously featured in a one-shot manga by Azuma called "Try! Try! Try!" The phrase Yotsuba to means "Yotsuba and," a fact reflected in the chapter titles, most of which take the form "Yotsuba and [something]."

The manga was licensed for English-language distribution by ADV Manga, which released five volumes between 2005 and 2007. Volume six was originally set to release in February 2008, but was indefinitely delayed. At New York Comic Con 2009, Yen Press announced that it had acquired the North American license for the series; it reprinted the first five volumes with new translations along with volume six in September 2009, and is continuing with later volumes.

The manga has received widespread acclaim from critics and audiences due to Azuma's artistic talent, writing, and the creation and development of the titular character, with the manga earning multiple awards and nominations.

Yotsuba&! is centered on Yotsuba Koiwai, a five-year-old girl who is energetic, cheerful, curious, odd, and quirky—so much so that even her own father calls her unusual. She is also initially ignorant about many things that a child her age would be expected to know—among them doorbells, escalators, air conditioners, and even playground swings. This naïveté is the premise of humorous stories whereby which she learns about—and frequently misunderstands—everyday things.

At the start of the series, Yotsuba and her adoptive father, Yousuke Koiwai, relocate to a new city with the help of Koiwai's best friend, an impressively tall man named Takashi Takeda, known as Jumbo. Yotsuba makes a strong impression on the three daughters of the neighboring Ayase family, Asagi, Fuuka, and Ena, after Ena meets Yotsuba trying to find out how a swing works. Most of her daily activities and misadventures often originate from interactions with these characters and more, such as Asagi's friend Torako, known as Tiger (from Yotsuba, the kanji for Tora is the same kanji in tiger).

The series has no consistent plot continuity—the focus of the stories is Yotsuba's daily voyage of discovery. Many chapters take place on successive days (for details, see List of Yotsuba&! chapters), so that the series follows, almost literally, the characters' daily lives. The tone can be summarized by the motto, used on chapter title pages and advertising: "Today is always the most enjoyable day" (いつでも今日が、いちばん楽しい日, Itsudemo kyō ga, ichiban tanoshii hi), or in the original translation, "Enjoy Everything".

In 1998, Azuma published a one-shot manga and two webcomics called "Try! Try! Try!", in which Yotsuba's adoptive father Yousuke Koiwai, Ena, Fūka, and Asagi first appear. Although some of these characters—including Yotsuba herself—are largely the same as in Yotsuba&!; Fūka has a different character design, a more mischievous personality, and a different spelling of her given name (in "Try! Try! Try!", it is written with the kanji 風 夏, meaning "wind-summer"; in Yotsuba&!, it is 風 香, meaning "wind-scent").

Azuma started writing Yotsuba&! a year after the conclusion of his previous manga, Azumanga Daioh. No crossovers between the two works occurred until the sixteenth volume of Yotsuba&! in 2025, which features a cameo appearance from Azumanga Daioh character Ayumu "Osaka" Kasuga, who is revealed to now be working as a P.E. teacher.