"Ohio" is a protest song and counterculture anthem written and composed by Neil Young in reaction to the Kent State shootings of May 4, 1970, and performed by Crosby, Stills, Nash & Young. It was released as a single, backed with Stephen Stills's "Find the Cost of Freedom", peaking at number 14 on the US Billboard Hot 100 and number 16 in Canada. Although a live version of "Ohio" was included on the group's 1971 double album Four Way Street, the studio versions of both songs did not appear on an LP until the group's compilation So Far was released in 1974. The song also appeared on the Neil Young compilation albums Decade, released in 1977, and Greatest Hits, released in 2004.

The song also appears on Neil Young's Live at Massey Hall album, which he recorded in 1971 but did not release until 2007.

Young wrote the lyrics to "Ohio" after seeing the photos of the incident in Life Magazine. On the evening that CSN&Y entered Record Plant Studios in Los Angeles, the song had already been rehearsed, and the quartet—with their new rhythm section of Calvin Samuels and Johnny Barbata—recorded it live in just a few takes. During the same session they recorded the single's equally direct B-side, Stephen Stills's ode to the war's dead, "Find the Cost of Freedom".

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