Although the educational function in agriculture is attracting growing attention as a kind of multifunctionality in agriculture, these services are not yet provided as a viable farm product. With regard to establishing a viable market for this service, this paper explores how the educational externality could be internalized by focusing on educational dairy farms in Japan and quantitatively evaluated the attitudes of operators toward establishing a viable service as revealed by a questionnaire survey. First, a conceptual framework was presented to express operators’ orientation toward an economically viable service by incorporating a stepwise internalization process of positive externalities with the help of a social learning network. Then, empirically, factors that determined this orientation, a viable service determinant function, were explored by the ordered logit model. The result showed that, first, the higher the number of visitors to the farm, the more operators were oriented toward a viable service while no connection with ordinary dairy production was shown. Second, social learning was effective for initiating the internalization process. Third, marketing skills became more important for upgrading the internalization level. Consequently, it is important to create opportunities for those farmers who want to provide consumers with educational services to learn a new role for agriculture and to stepwisely establish a new income source.