Abstract: The main goal of the article is to present the core opportunities as well as problems of the Regional Security Complex Theory (RSCT) by Barry Buzan and Ole Wæver and the security communities theory referring to Karl Deutsch's assumptions and developed by Emanuel Adler and Michael N. Barnett. The research question the paper tries to answer is whether the position between realism and social constructivism of these two theories enriches them or makes them even more problematic by maintaining the dichotomy between objective and ideational factors. The structure of the article is as follows. First, after a brief introduction to the new "region defining" according to social constructivism, the main assumptions and limitations of the RSCT will be presented. Secondly, the paper draws attention to security communities theory also focusing on its main assumptions and problems stemming from its "between position". The conclusion shows the problems that scholars may experience with both theories, which are a result of their situation between realism and social constructivism. Consequently, neither the concept of security communities nor RSCT can be examples of theoretic syntheses or propositions for conducting research in the spirit of analytic eclecticism, but are rather examples of integrative pluralism.