Widespread outbreaks of avian influenza occurred in 2004–2005. The outbreaks resulted in extensive losses for the poultry sector in East and South East Asia. Thailand suffered a tremendous impact from the disease. Later, in 2006, there was another outbreak of the aforementioned disease in poultry production clusters (PPCs) in Nakhon Phanom province in the northeastern region of Thailand. In this study, we conducted an intervention by working together with the Department of Livestock Development officials to improve the biosecurity level of PPCs in this province. The methods employed in the intervention included meetings to build understanding and hear about various ideas and problems among stakeholders; instructions; having the farmers perform self-evaluations of the level of biosecurity on the farms; and measures for motivating farmers, e.g., farm contests and handing out awards. The results revealed the following information: After intervention, attraction to wild bird of poultry farms in PPCs decreased (p < 0.05), because the farmers cut down trees around farm and poultry housing. Moreover, biosecurity system planning inside farms in PPCs increased (p < 0.05). The scores for biosecurity system planning inside farms that increased following the intervention are a positive sign that farmers will continue to develop better biosecurity systems on their farms.