Critical mass is the amount of fissile material needed to sustain nuclear fission.
Critical mass may also refer to:
Science and technology
- Critical mass (sociodynamics), a stage in social-system innovation
- Critical mass (software engineering), a stage in the product life cycle of software
Organizations
- Critical Mass (cycling), a form of direct action involving large groups of bicycle riders
- Critical Mass (pressure group), a UK political pressure group
- Critical Mass Energy Project, an anti-nuclear umbrella group founded by Ralph Nader
- Critical Mass Journal, published in 1977 by the Critical Mass Energy Project
- Critical Mass, a co-working center sponsored by the New England Venture Capital Association
- Critical Mass, a robotics team of the Dwight-Englewood School in Englewood, New Jersey
Literature
- Critical Mass (book), a 2004 book by Philip Ball
- Critical Mass (2013 book), a 2013 novel by Sara Paretsky
- "Critical Mass" (Pohl and Kornbluth short story), a 1962 story by Frederik Pohl and Cyril M. Kornbluth
- "Critical Mass" (Arthur C. Clarke short story), a 1949 short story by Arthur C. Clarke
- Critical Masses: Opposition to Nuclear Power in California, 1958–1978, a 1998 book by Thomas Wellock
- Critical Mass, a 1990 seven-issue comic book anthology printed under Epic Comics's Shadowline Saga imprint
Film and television
- Critical Mass, a 1971 experimental short film by Hollis Frampton
- Critical Mass (anime), a subdivision of the video publisher and distributor Right Stuf Inc.
- Critical Mass (film), a 2000 film starring Treat Williams and Lori Loughlin
- "Critical Mass" (Stargate Atlantis), an episode of Stargate Atlantis
Gaming
- Duke Nukem: Critical Mass, a shooter game developed by Frontline Studios
- Critical Mass (1985 video game) or Power!, a computer game by Durell Software
- Critical Mass (1982 video game), an adventure game by Sirius Software
- Critical Mass, a set of collectible miniature game figures by HeroClix
Music
Bands
- Critical Mass (American band), a ska band formed in 1992
- Critical Mass (Canadian band), a Catholic rock band formed in 1997
- Critical Mass (Dutch band), a Dutch happy hardcore group
Albums and songs
- Critical Mass (Dave Holland album), 2006
- Critical Mass (Threshold album), 2002
- Critical Mass (Matthew Shipp album), 1995
- Critical Mass (Ra album), 2013
- "Critical Mass", a song by Aerosmith from Draw the Line
- "Critical Mass", a song by Nuclear Assault from Handle with Care
- "Critical Mass", a song by Chrome from Half Machine Lip Moves