Joomla CMS evolved as the result of a fork of Mambo by the Joomla CMS development team on August 17, 2005. At that point in time, the Mambo name was trademarked by Miro International Pty Ltd, who formed a non-profit foundation and stated their purpose as to finance the project and shield it from law suits. The Joomla CMS development team said that quite a few of the provisions of the foundation structure contradicted previous agreements decided upon by the elected Mambo Steering Committee, lacked the necessary consultation with key stake-holders and, which is even more important, new foundation added to provisions that violated core open source principles.
The Joomla CMS team created a site called OpenSourceMatters to distribute information to users, coders, web designers and the online community in general. The project team leader Andrew Eddie, also known as "MasterChief" authored an open letter to the public which came out on the announcements spot of the public forum at mamboserver.com.
More than one thousand individuals registered as members of the opensourcematters.org site in not more than a day, most encouraged and supported the idea, and the web site received the slashdot effect due to this fact. Miro Boss Peter Lamont presented a open public reaction to the development team in an document known as "The Mambo Open Source Controversy - 20 Questions With Miro". This event led to hot debate within the free software community about the definition of "open source". Forums at many other open source projects were full of with postings for and against both sides.
In the two weeks right after Eddie's announcement, teams had been re-organized, and the community grew even larger. Eben Moglen and the Software Freedom Law Center (SFLC) assisted the Joomla CMS core team beginning in August 2005, as indicated by Moglen's blog entry from that date and a related OSM announcement. The SFLC continue to supply legal guidance to the Joomla! project.
On August 18, 2005, Andrew Eddie asked community suggestions names for the project. The core team mentioned that the final decision for the project name would be made based on community suggestions. The core team eventually selected a name that was not on the list of suggested names provided by the community. On September 1, 2005 the new name, "Joomla!", was introduced. The name is the English transliteration of the Arabic word jumla which can be interpreted as "all together" or "as a whole", as well as "sentence" (as in, phrase).
On September 6, 2005, the development team called for logo submissions from the community, invited the community to vote on the logo preferred, and announced the community's decision on September 22, 2005. Following the logo selection, brand guidelines, a brand manual, and a set of logo resources had been then published on October 2, 2005 for the community's use.
Joomla! (Joomla 1..) was released on September 16, 2005. It was a re-branded release of Mambo 4.5.2.3 which, itself, was combined with other bug and moderate-level security fixes.
Joomla! won the Packt Publishing Open Source Content Management System Award in both 2006 and 2007.
On October 27, 2008, PACKT Publishing announced Johan Janssens the "Most Valued Person" (MVP) for his work as one of the lead developers of the 1.5 Joomla Framework and Architecture. In 2009 Louis Landry received the "Most Valued Person" award for his role as Joomla architect and advancement coordinator.
Joomla! version 1.5 was released on January 22, 2008.
At the end of October 2009 a second alpha version of 1.6 was made available for testing purposes.
By October, 2009, the 2009 Open Source CMS Market Share Report arrived at the conclusion that Joomla is the web's most popular open source content management system. That conclusion was based on an extensive analysis of rate of adoption patterns and brand strength and was backed by a study of customer survey.