The importance of sustainable development issues requires the engagement of all stakeholders in decision-making processes, as well as developing tactics and strategies. The complexity of this task increases on regional and international levels, where a huge amount of interests intersect or even contradict each other. To develop proper policy measures towards sustainability, it is essential to use appropriate performance assessment. Regardless of the existence of some macro estimation methods, vast gaps in practical use still remain. In this paper, a set of methods for assessing the sustainability performance of countries is outlined and discussed. The main advantages and weaknesses of the prevalent approaches are considered. Using available statistical data from open sources, sustainability performance assessment in countries within the Baltic Sea Region in the years 2005–2010 is carried out according to different methods and discussed, thus obtaining the profile of sustainability performance for countries in the Baltic Sea Region. The results of the calculations may be used for sharing with communities, detecting sustainability gaps in the countries’ economies, substantiating national and regional sustainable development strategies, and analyzing the investment attractiveness of the given region.