Men's professional football is the biggest sport in the world, producing (by our estimate) US $33 billion a year. All is not well in the sector, however, with regular scandals raising questions about the role of money in the sport. The 2015 turmoil around FIFA is obviously the most well known example, creating a crisis in confidence in the sector. This study examines these questions, and the financial integrity weaknesses they reveal; it also offers ideas to strengthen the weaknesses.