In recent years, the discussion about both the university's sustainability and social responsibility has risen above average. In the international academic discourse, the number of researches and publications focusing on these phenomena has increased drastically and the terms of corporate social responsibility and sustainable development in their relation to the university have gained increasing popularity. However, despite the multiple publications, a common definition of corporate social responsibility has not been offered so far, not to mention a reliable definition of the university's social responsibility, which proved to be even more complicated than that of the corporation, due to its multi-level social mission. Besides, the notion of the university's sustainability, which has also been paid much attention to, when considered more closely, turned out to be considerably overlapping with the notion of the university's social responsibility in many aspects. The absence of reliable differentiation between the terms and trustworthy concept of the phenomena's interrelation and interaction within the university's internal environment, has raised a broad and unspecified discussion in economics, sociology, business management, and other fields of knowledge including theories organisational behaviour and leadership. Also, as the university's social responsibility is largely aimed at the external environment, which stipulates to a larger extent its sustainability, the dependence of both phenomena on the university's interrelations with the external stakeholders deserve profound investigation. To begin with, the authors base their considerations on the definition of sustainable development provided by Brundtland and the model of the triple-bottom-line, as well as on a profound literature study. Further on, the authors attempt to differentiate the phenomena of social responsibility and sustainable development, their interrelation and interdependence in both the university's internal and external environment. The authors' theoretical research is supported with benchmarking and consideration of the world leading universities' best practices, which have been generalised and structured in a model of the university's social responsibility and sustainability interrelation in its both environments – internal and external. The paper raises a number of important issues including those of the role of higher education for national and global sustainable development and the impact of recent global trends on the sustainability of national systems of higher education and every university in the global higher education environment, as well as the university's social responsibility before the main stakeholders of higher education, and responsibility of the stakeholders before the universities and the society in the aspect of its sustainable development.