The potential of Extended Education (EE) for subject-specific and socio-emotional learning has been confirmed across countries. However, many studies show that socially disadvantaged children participate less frequently and intensely than their more advantaged peers. Research shows that there are numerous potential explanations for differences in participation in respective offerings—from individual to social and regional factors. In our article, we focus on one single aspect of the rich body of available knowledge: We offer tentative answers to the question which institutional conditions support the access of disadvantaged children of primary school age to Extended Education. In our contribution, we focus on this question with particular emphasis on the role of the relationship between educational institutions and parents for children’s participation. The empirical basis of the article are perceptions of this question from international experts who were consulted as part of the project “Educational Success and Social Participation of Socially and Educationally Disadvantaged Students with Migration Background in Extended Education” (abbr. in German: GeLeGanz). The interviewees emphasise the enabling function of communication and interaction between educational institutions and families as crucial aspect for participation of children from disadvantaged homes. Our findings contribute to better understanding how the design of communication and cooperation practices around educational offerings can promote the participation of socially disadvantaged children in Extended Education.