Contributions to Scilab are welcomed and possible by:

• Translating Scilab (help pages, menus, messages...)
• Developing external modules to add some functionalities to Scilab in a specific application domain
• Becoming an official Scilab contributor and then being able to directly modify Scilab source code or add new functionalities for future releases

You already have an idea of development for Scilab?

Scilab Enhancement Proposals (SEP) are a management tool to encourage and facilitate Scilab development process. Existing SEPs and a template are available here.
Via SEPs, Scilab users can directly send to Scilab R&D team their development ideas via the development mailing list: dev@lists.scilab.org