The polls opened at a "Facebook Site Governance Vote" page at the social network and will close June 8 at 900 am (1600 GMT).
The vote will be considered binding if more than 30 percent of Facebook's active members take part, communications vice president Elliot Schrage said in a blog post.
The company has since grown to nearly a billion users, moved to the former Sun Microsystems campus in the city of Menlo Park, and raised billions of dollars by going public with an initial public offering of stock in May.
"Today we are posting the proposed revised versions of both documents and asking you to join our second global site governance vote," Schrage said. "We strongly encourage you to participate."
Those interested in voting were directed to: facebook.com/fbsitegovernance/app_130362963766777.