The Big Bang: UK Young Scientists' and Engineers' Fair is an annual three-day event designed to promote science, technology, engineering and maths (STEM) careers to young people aged 7-19 through experiential learning. It is supported by stakeholders from business and industry, government and the community, and brings together people from various backgrounds to explore the ever-changing world of STEM, while endeavouring to promote and encourage future ambassadors. The Big Bang event took place first in London in 2009 and was attended by 6300 young people. Building on this success, The Big Bang 2010 focused on exciting and stimulating young people, including those who have never before considered a career in the sector. In this article, the author reports on the success of The Big Bang 2010. (Contains 4 figures.)