Led Zeppelin III is the third studio album by the English rock band Led Zeppelin, released on 5 October 1970. It was recorded in three locations. Much of the work was done at Headley Grange, a country house, using the Rolling Stones Mobile Studio. Additional sessions were held at Island Studios and Olympic Studios in London. As with the prior album, the band eschewed the use of guest musicians, with all music performed by band members Robert Plant (vocals), Jimmy Page (guitars), John Paul Jones (bass, keyboards), and John Bonham (drums). The range of instruments played by the band was greatly enhanced on this album, with Jones especially emerging as a talented multi-instrumentalist, playing a wide range of keyboard and stringed instruments, including various synthesizers, mandolin and double bass, in addition to his usual bass guitar. As with prior albums, Page served as producer on the album, with mixing done by Andy Johns and Terry Manning.

The album showed a progression from straightforward rock towards folk and acoustic music. While hard rock influences were still present, such as on "Immigrant Song", acoustic-based songs such as "Gallows Pole" and "That's the Way" showed Led Zeppelin were capable of playing different styles successfully. The band wrote most of the material themselves, but as with prior records, included two songs that were re-interpretations of earlier works: "Gallows Pole", based on a traditional English folk song, by way of American singer Fred Gerlach; and "Hats Off to (Roy) Harper", a reworking of a blues song by Bukka White. The acoustic material developed from a songwriting session between Plant and Page at Bron-Yr-Aur cottage in Wales, which influenced the musical direction.

The album was one of the most anticipated of 1970, and its shipping date was held up by the intricate inner sleeve design based around a volvelle, with numerous images visible through holes in the outer cover. It was an immediate commercial success upon release and topped the UK and US charts. Although many critics were initially confused over the change in musical style and gave the album a mixed response, Led Zeppelin III has since been acknowledged as representing an important milestone in the band's history and a turning point in their music.

By 1970, Led Zeppelin had achieved commercial success in both the UK and the US with their first two albums. They were determined to have a proper break, having recorded most of Led Zeppelin II in various locations while on tour, financing the sessions with the album sales and tour receipts. Following an exhausting concert tour of North America that spring, lead singer Robert Plant recommended to guitarist and producer Jimmy Page that they should retreat to Bron-Yr-Aur, an 18th-century cottage in Snowdonia, Wales, on a hilltop overlooking the Dyfi Valley, three miles (4.8 km) north of the market town Machynlleth. Plant had spent holidays there with his family.

This remote setting had no running water or electric power, which encouraged a slight change of musical direction for the band towards an emphasis on acoustic arrangements. Page later explained that the tranquillity of Bron-Yr-Aur stood in sharp contrast to the continual touring of 1969, affecting the overall tone of the songwriting and dominance of acoustic guitars. His playing was influenced by folk guitarists Davey Graham and Bert Jansch, who regularly used alternative guitar tunings. Plant also recalled the band were "obsessed with change" and enjoyed listening to John Fahey. The band specifically wanted a change in direction, to show they could play any style of music they wanted.

The first recording sessions for Led Zeppelin III took place at Olympic Studios in November 1969. A press statement from manager Peter Grant said the group were recording a non-album track to be released as a single, but this was ultimately abandoned. Further sessions took place towards the end of the year, in between touring, before the decision was made to stop working and take a break at Bron-Yr-Aur. After preparing material for the album there, Page and Plant were joined by drummer John Bonham and bassist/keyboardist John Paul Jones at Headley Grange, a mansion in East Hampshire, to rehearse the songs. The rural atmosphere gave a relaxed feel to the sessions, and the band found it to be a more enjoyable environment in which to develop songs than a studio in the city.

The album was recorded between May and June 1970 at Headley Grange (using the Rolling Stones Mobile Studio) and at Olympic, with further recording at Island Records' Island Studios in Notting Hill the following month. Mixing took place at Ardent Studios, Memphis, in August 1970, partway through the group's sixth American concert tour. The album was produced by Page and engineered by Andy Johns and Terry Manning. Page had first met Manning when the latter's band, Lawson and Four More, had supported Page's old band the Yardbirds in 1966. Manning had been to several Led Zeppelin shows, and this led to Page asking him to engineer the new album.

Led Zeppelin III marked a change in focus for the band, from late 1960s hard rock to a more acoustic-based sound. These styles had been present to a lesser degree on the band's first two releases, such as "Babe I'm Gonna Leave You" and "Ramble On", from the first and second albums, respectively. However, on this album, the group used more acoustic arrangements, and they would remain prominent to various degrees in the group's later releases. With Led Zeppelin III, the group's songwriting dynamic also changed, from Page's domination of the first two albums towards a more democratic situation in which all four group members contributed their own compositions and ideas. Plant wrote all of the lyrics, with the exception of "Tangerine".