The independent investigation into historical child sex abuse in football may have to sift through five million documents, BBC Sport has learned.
The inquiry, led by barrister Clive Sheldon QC, was started by the Football Association in December, after a series of allegations from former players.
The full scale of the review into the scandal can now be revealed.
Investigators have started searching 5,000 boxes of FA archives - each containing up to 1,000 pages.
The inquiry will last several months, with a final report not expected to be published until 2018.
The review is asking anyone involved with football who wishes to provide information about the way in which clubs or the FA dealt with concerns over child sex abuse between 1970 and 2005 to come forward.
Sheldon - an expert in safeguarding and child protection - has written to all 65,000 affiliated clubs seeking assistance, and has begun meeting individuals who can contribute.
Clubs and officials who fail to co-operate could face disciplinary action.
Sheldon will investigate whether there is any evidence of a paedophile network having operated within the sport, and will take into account girls' football.
He will also look into the use of confidentiality agreements - or 'gagging clauses' - by clubs following the revelation Chelsea paid a former player £50,000 on condition he kept quiet about the abuse he said he had suffered by the club's former scout Eddie Heath.
Sheldon will make recommendations about the current safeguarding system if he identifies weaknesses, and refer any potential criminal offence to Operation Hydrant, the unit co-ordinating police investigations into child sexual abuse across the UK.
Police have identified more than 250 potential suspects and 560 victims, with 311 clubs involved.