The article deals with the problem of updating the educational strategy of the school by integrating additional education into the educational space of the school. The aim of the article is to substantiate the socio-pedagogical conditions of supplementary education integration into the educational space of the school. The research methodology is based on the system and network approaches. Evidence base served as the results of experimental work on approbation of the program “School of Cosmonautics” to integrate additional education in the educational space of the school, obtained through the methods of analysis, design, comparison, questioning, interviews, implementation of a system of measures, integrated in its content, comprehensive in types, forms and technologies of educational activities. Results of the study. The educational space of the school is considered as a pedagogically organized process, which on the basis of integration includes interested subjects of the educational environment, as well as the result of proactive activities of its internal and external elements, between which there are relations aimed at ensuring the implementation of the subjective position of the schoolchild. Within the integrative model of the educational space of the school there have been worked out educational programs in which individual components of activities could be combined with each other depending on the interests and abilities of students, school traditions, which allowed forming the content of all modules of the educational work program. The educational process was carried out in different environments and situations with the implementation of the principle of joint activities through the creation of socio-pedagogical conditions. As a result, the positive dynamics of the development of educational space, integrating and combining the potential of additional and general education, proved the presence of qualitative changes in the value orientations of schoolchildren. Conclusion. Experimental work has confirmed the effectiveness of additional education as an equal subject of integration processes in the educational space of the school to ensure the creative interaction of all subjects of educational space. The results of approbation of the program of integration of additional education in the educational space of the school confirmed its significance and reproducibility as an experience of expanding the possibilities of external and internal integration.