A science festival is a festival that showcases science and technology with a similar atmosphere to an arts or music festival, and that primarily targets the general public. These public engagement events can be varied, including lectures, exhibitions, workshops, live demonstrations of experiments, guided tours, and panel discussions. There may also be events linking science to the arts or history, such as plays, dramatised readings, and musical productions. The core content is that of science and technology, but the style comes from the world of the arts.

The modern concept of a science festival comes from the city of Edinburgh in 1989. The choice of Glasgow as European Capital of Culture for 1990 took Edinburgh by surprise and stimulated it to rebrand itself as a city of science, building on the success of a series of big urban developments led by its Economic Development Department. A senior member of the development team, Ian Wall, proposed that Edinburgh should highlight its new image by complementing its world-famous autumn arts festival with a new type of spring event for which he coined the phrase 'science festival'. Reaction was mixed, with some organisations doubting whether science could be packaged in an arts format. Even so, the city put resources behind the idea, appointing a director and project team, and in April 1989 the first Edinburgh International Science Festival took place.

Edinburgh's success led to the development of science festivals in many other parts of the world. The British Science Association restructured its annual meeting, originally established in 1831 as a discussion forum for scientists, to turn it into the British Science Festival of today. The town of Cheltenham—famous for its jazz, music, and literature festivals—added science to its portfolio with the creation of the Cheltenham Science Festival in 2002.^{[citation needed]}

Realizing the key importance of science festivals science organizations and funding bodies put ever more emphasis on outreach to foster public understanding both of the results and the wider relevance of science. Recent years have seen the creation of a number of new science festivals as forms of public engagement. An umbrella organization for European science festivals and other science communication events, the European Science Events Association (EUSEA), was formed in 2001 and now has approximately 100 member organizations from 36 countries.

The concept spread to Sweden in 1997 with The International Science Festival in Gothenburg which is an annual festival in central Gothenburg, Sweden with thought provoking science activities for the public. The festival is visited by about 100,000 people each year. This makes it the largest popular science event in Sweden and one of the largest popular science events in Europe.

The spread of science festivals within the United States is relatively recent. One of the earliest examples is Wonderfest, an annual Bay Area science festival that began in 1998. Additionally, the annual meeting of the American Association for the Advancement of Science includes a number of public events. Focusing on one particular science, the physics festival "Mastering the Mysteries of the Universe", was held in Atlanta, Georgia, in 1999 in association with the centennial of the American Physical Society. Since 2004, there has been a science festival in Pittsburgh (the SciTech festival; from 2005 on known as the SciTech Spectacular), and new science festivals have been held in Cambridge, Massachusetts (the Cambridge Science Festival, first held in April 2007); and in New York City (the World Science Festival held at the end of May 2008); and in March 2009, San Diego hosted the first west coast science festival, the San Diego Science Festival founded by Larry Bock.

As of 2009^[update] the Science Festival Alliance, a consortium of major festivals formed with a 3-year NSF grant, has supported the growth of independent regional science festivals, with an initial emphasis on celebration in communities throughout the US.

In September 2010, the North Carolina Science Festival became the first statewide science festival in the United States, presenting more than 400 events across the state over a two-week span. The second NC Science Festival was held April 13–29, 2012, and the festival is now an annual event. Morehead Planetarium and Science Center at UNC-Chapel Hill founded the North Carolina Science Festival and continues to administer it.