The existence of home advantage in football is a well known and well documented fact. However the precise causes and the way in which they affect performance are still not clear. A comprehensive review is made of published research under the main hypothesized explanations for home advantage in football which are: crowd effects, travel effects, familiarity, referee bias, territoriality, specific tactics, rule factors and psychological factors. Their interactions, and other factors that need to be taken into account when investigating home advantage, are considered.