New sincerity (closely related to and sometimes described as synonymous with post-postmodernism) is a trend in music, aesthetics, literary fiction, film criticism, poetry, literary criticism and philosophy that generally describes creative works that expand upon and break away from concepts of postmodernist irony and cynicism.

Its usage dates back to the mid-1980s; however, it was popularized in the 1990s by American author David Foster Wallace.

"New sincerity" was used as a collective name for a loose group of alternative rock bands, centered in Austin, Texas, in the years from about 1985 to 1990, who were perceived as reacting to the ironic and cynical outlook of then-prominent music movements like punk rock and new wave. The use of "new sincerity" in connection with these bands began with an off-handed comment by Austin punk rock artist and author Jesse Sublett to his friend, local music writer Margaret Moser. According to author Barry Shank, Sublett said: "All those new sincerity bands, they're crap." Sublett (at his own website) states that he was misquoted, and actually told Moser, "It's all new sincerity to me ... It's not my cup of tea." In any event, Moser began using the term in print, and it ended up becoming the catch phrase for these bands.

Nationally, the most successful "new sincerity" band was the Reivers (originally called "Zeitgeist"), who released four well-received albums between 1985 and 1991. True Believers, led by Alejandro Escovedo and Jon Dee Graham, also received extensive critical praise and local acclaim in Austin, but the band had difficulty capturing its live sound on recordings, among other problems. Other important "new sincerity" bands include Doctors Mob, Wild Seeds, and Glass Eye. Another significant "new sincerity" figure was the eccentric, critically acclaimed songwriter Daniel Johnston.

Despite extensive critical attention (including national coverage in Rolling Stone and a 1985 episode of the MTV program The Cutting Edge), none of the "new sincerity" bands met with much commercial success, and the "scene" ended within a few years.

Other music writers have used "new sincerity" to describe later performers Arcade Fire, Conor Oberst, Cat Power, Devendra Banhart, Joanna Newsom, Neutral Milk Hotel, Sufjan Stevens, Idlewild, as well as Austin's Okkervil River Leatherbag, and Michael Waller.

Critic Jim Collins introduced the concept of "new sincerity" to film criticism in his 1993 essay titled "Genericity in the 90s: Eclectic Irony and the New Sincerity". In this essay he contrasts films that treat genre conventions with "eclectic irony" and those that treat them seriously, with "new sincerity". Collins describes,

the "new sincerity" of films like Field of Dreams (1989), Dances With Wolves (1990), and Hook (1991), all of which depend not on hybridization, but on an "ethnographic" rewriting of the classic genre film that serves as their inspiration, all attempting, using one strategy or another, to recover a lost "purity", which apparently pre-dated even the golden age of film genre.