The research results aimed at specifying the term of «business cooperation» are presented. The author gives the definition of «business cooperation». Its nature and conditions of functioning being content of preparing primary school-aged children for business cooperation are revealed. The principles of business cooperation are described. Readiness of primary school-aged children for business cooperation is viewed as a purpose and result of preparing them for such kind of interaction. At the same time readiness for business cooperation is seen as integral, dynamic personality quality aimed at effective interaction of shared experience subjects on the basis of personality attitude to business cooperation, value attitude toward it and its subjects, knowledge and skills of a person, and communicative reflection.