Williams has been suspended since the 2005 season for violating the league's drug policy.
"Ricky Williams was notified this morning by Commissioner (Roger) Goodell that he has been reinstated as an NFL player," the league said in a statement. "Williams can begin attending team meetings and practicing immediately, but will not be eligible to play in games until Week 12 when the Dolphins play at Pittsburgh (Monday night, Nov. 26). The Dolphins will receive a roster exemption for Williams for up to two weeks when he begins practicing, starting no later than Monday."
Williams was suspended in April 2006 for his fourth violation of the league's anti-drug policy. He then signed a one-year deal with Toronto of the Canadian Football League, where he ran for 623 yards. He missed two months of the 2006 season with a broken arm.
His reinstatement to the NFL does not guarantee he will be on the Miami roster. Miami Coach Cam Cameron said Wednesday that he and Williams, "will sit down and visit."