Aoxomoxoa is the third studio album by American rock band the Grateful Dead, released on June 20, 1969, by Warner Bros.-Seven Arts.

It is the only studio release to include pianist Tom Constanten as an official member (he had contributed to the previous album and played live with the band from November 1968 to January 1970).

It was also the first time the band would showcase acoustic arrangements (as on "Mountains of the Moon", "Rosemary", and "Dupree's Diamond Blues"), which would become the focus of the next two studio albums.

[6] The initial version, with the working title Earthquake Country (a Bay Area reference), was abandoned when Ampex manufactured and released the first 16-track multitrack recording machine (model number MM-1000).

The end result was dense and cumbersome in places, and all that studio time cost us a fortune, but we were experimenting on the sonic frontier, exploiting cutting-edge technology.

"[8] Indeed, the lengthy sessions for the album would put the band deeper into debt with Warner Bros. Records — specifically, a total cost of $180,000 (US$1,495,535 in 2023 dollars[9]) for Aoxomoxoa.

"[10] Along with help from guest musicians such as John "Marmaduke" Dawson and David Nelson, Lesh played acoustic bass for the first time.

[12] One fan legend considers the words "Grateful Dead" on the front of the album, written in large, flowing capital letters, to be an ambigram that can also be read "we ate the acid".

People have surmised over the years that you could read the Grateful Dead lettering on the front cover as We Ate the Acid which, I suppose, is true enough, if you look at it just right.

"[8] The man sitting on a horse in the back cover photograph is jazz pianist Vince Guaraldi, a friend of the band.

[21] Years later, AllMusic's Fred Thomas said "the Grateful Dead reached their true peak of psychedelia" with the album, embellishing "the exploratory jamming and rough-edged blues-rock of their live shows" with "overdubbed choirs, electronic sound effects, and layers of processed vocal harmonies.

"[19] According to Adam Bouyamourn of The National, the album's "iconoclastic acid rock … combined free jazz, improvisation and psychedelia".

The result, with the same catalog number (WS1790) and perhaps brighter sound, but with much of the original's experimental character removed, can be identified by the "Remixed September, 1971" legend on the back cover.

[25] Since this set stayed in print through the late 1970s, it provided a sample of the original mix for some years after the full album was only available in the remixed version.