The findings of the independent review mirrored the findings of Washington State's own internal review of the allegations, which was released last month.
Former Washington State receiver Marquess Wilson contended near the end of last football season that players were suffering physical and mental abuse at the hands of coaches. Wilson, who quit the team, subsequently recanted his allegations.
But university President Elson Floyd asked the school and the Pac-12 to investigate the charges anyway.
"I am pleased with the outcome of both reviews," Floyd said in a press release Tuesday. "The well-being of all WSU students is our highest priority and it was important to take seriously allegations against the program."
The Pac-12 report was compiled after 20 interviews with coaches, players, parents of players and athletic department staff members.
Wilson contended in a memo sent to journalists on Nov. 10 that he quit the team prior to the UCLA game as a protest to "physical, emotional and verbal abuse" by the coaching staff. He complained that coaches would "belittle, intimidate and humiliate us." He did not provide any details.
The same night he sent the letter, Wilson sent a text message to athletic director Bill Moos in which he recanted those allegations.
Leach also denied the allegations of abuse.
Wilson, who was a junior this season, is the leading receiver in Washington State history.
Leach was fired from Texas Tech after the 2009 season after claims that he mistreated a player suffering from a concussion. Leach disputed the allegation and it was not proven. Leach has sued Texas Tech, contending he was fired so the school could avoid a large payment that was due to him at the end of that year.