The band's named is taken in honour to an agricultularist, and Ian explains: "I was not the author of the Jethro Tull name. The original Jethro Tull was an 18th century agriculturalist. He was also something of an inventor. He invented the seed drill. He built his first prototype seed drill from the foot pedals of his local church organ. When it was suggested as one of our weekly names for our band in its early days by our agent we said 'ok, we'll be Jethro Tull this week.' The reason for all that was that we were not a terribly good group when we first started, and the only way we could get re-booked into the clubs we played at was to pretend to be somebody different every week... often we didn't know who we were-- the agent forgot to tell us-- so we would arrive at some club, and we'd look down the list of bands playing... whichever one we'd never heard of before, we knew that must be us. The time we got asked back to the Marquee club we had to stick with the name we had that week, which happened to be Jethro Tull. It's not a name I feel particularly wonderful about. I feel faintly embarrassed about it because it's not an original name. It's somebody else's name."

The cover art for ''Thick As A Brick'' took longer to make than the whole song (43:50).

Black Sabbath guitarist Tony Iommi played guitar for Jethro Tull briefly in 1968 following the departure of Mick Abrahams. The only recording of him with Jethro Tull is on The Rolling Stones Rock and Roll Circus although his guitar is not heard as all of the music (excepting Ian Anderson's vocals and flute) was dubbed in afterwards. It was a one-off performance and he returned to Black Sabbath in January 1969.

Jethro Tull's album Crest of a Knave won the 1989 Grammy Award for Best Hard Rock/Metal Performance, beating odds-on favorites Metallica with their album ?And Justice for All. Under advisement from their manager, no one from the band turned up to the award ceremony, as they were told that they had no chance of winning. In response to the criticism they received over the award, the band took out an advert in a British music periodical with the line, "The flute is a (heavy) metal instrument!" In 2007, the win was named one of the 10 biggest upsets in Grammy history by Entertainment Weekly.