The community and the user base is what differentiates a successful open source project from a non-successful one. Users are able to contribute to Mantis via the following means:

• Register on http://www.mantisbt.org/bugs and report bugs or feature requests. Also contribute your opinion on issues that are already reported by other users. Diversity of needs and opinions guarantees that we develop a product that is generic enough and simple enough for all our users.
• Install non-stable release, test them and provide feedback. The recommendation is to do such testing on a backup copy of your data. Unless you are comfortable PHP and Mantis code base, it is generally recommended to keep your production releases on stable Mantis releases.
• Whenever your learn something that wasn't readily available in the documention, contribute it back. You can contribute such information to the forums, the wiki, or the manual as notes.
• Visit website often, read the documentation and the wiki, review Requirements, provide feedback.
• Visit our sponsors and affiliates, get to know what they do, do business with them.
• Register your oragnization on the Mantis Users Directory by contacting vboctor -at- users -dot- sourceforge -dot- net.
• Talk to your organization to donate to or sponsor Mantis.
• Recommend Mantis to others.

See Contributing to MantisBT for more details.