The inquiry has been studying corruption and collusion in the province's construction industry, organized crime influence in the industry and corruption within construction unions.
The Charbonneau Commission has heard from more than 100 witnesses since its launch in October 2011.
Now it wants to hear from others.
Organizations and members of the public can submit their proposals, possible solutions and analysis through the commission's website until June 20.
Some people will be invited to appear in person.
Inquiry chair France Charbonneau says the briefs will be integral to the commissioners as they write a final report that is due by April 2015.
The inquiry issued a mid-term report last month saying it was too soon to draw conclusions.