Thailand is the 2nd largest seed exporter in Asia after China, and maize contributes to the largest export revenue of all seed exports from Thailand. Leading multinational seed companies have invested in research facilities and breeding programs in Thailand since the late 1970s, and this makes Thailand one of important bases of maize seed production. Currently there are five multinational companies integrated in maize seed production in Thailand while many small local companies operate at national or provincial scale. This paper addresses different contract models operated by seed companies, and analyze the factors contributing to the participation of growers in maize seed production contracts.