The paper presents features of monodisciplinary, polydisciplinary and interdisciplinary research in education, and the application thereof in adult education research. Differences in the presence of the monodisciplinary and the polydisciplinary approaches in the adult education theory (andragogy) of pedagogical origin, and the adult education theory based on educational sciences, are stressed. Furthermore, there exists a trend towards the interdisciplinary research of adult education, and the tendency for andragogy to synthesize the knowledge from other educational sciences in the adult education domain, representing the added scientific value thereof, thanks to which it may be considered a separate educational science. Implications of the scientific development of andragogy in relation to the adult education study are analyzed.