The aim of the article is to identify and define changes in the importance of?informal institutions to Generation Y from Central and Eastern Europe in the process of?acquiring knowledge in several dimensions: trust, social groups and networks, social activity,?as well as a comparison of informal institutions between young people of different?nationalities. The article examines whether the knowledge gained by the Millennials from?Central and Eastern European (CEE) countries during higher education is connected with the?change of social competences reflected in the changes of informal institutions. The results of a?survey carried out among Millennials who are educated at universities in Poland, Lithuania?and Slovakia were used. The article takes into account such categories of informal institutions?as social standards, trust, networks, informal social activities. The results of the research?indicated that the social competences of young people in the dimension of informal?institutions do not change significantly under the influence of academic education and remain?at a low level in many dimensions. In addition, it was found that there is a diversity in the?importance of informal institutions to CEE Millennials by country of origin.