This research aims to explore children's career interests and knowledge based on Holland's Theory, and to test the fit of the model of lower-grade primary school students' career knowledge using the same theory. The research sample was 576 lower-grade primary school students in Daerah Istimewa Yogyakarta. Quantitative descriptive technique was employed to describe children's career interests and knowledge, while Confirmatory Factor Analysis was used to test the model fit of the data. The results show that the social dimension of Holland's theory becomes the students' highest orientation in career interests and knowledge. The five careers most preferred by the children are teacher, principal, doctor, singer, and police officer while the five careers least preferred by the children are administration employee, salesperson, counselor, sculptor, and model. Moreover, the careers whose knowledge is mostly learnt by the students are teacher, principal, driver, police, and doctor. On the other hand, the five careers whose knowledge is the least learnt by the students are administration employee, counselor, salesperson, sculptor and agriculture engineer. Finally, the research reveals that the career knowledge of the children fits to Holland's concept. It implied that Holland's theory is suitable used for improving children's career interests and knowledge in guidance and counseling program.