MOMUS–Museum of Modern Art–Costakis Collection is entrusted with the preservation, study, and promotion of modern and contemporary visual art, with particular emphasis on the internationally renowned Costakis Collection. The Collection comprises works of art and archival material from the historical avant-garde in the Russian Empire and the Soviet Union (1900–1930), as well as works by Greek and international artists representing the diverse developments of modernism.

The museum's main organisational goals include educating the public, producing scientific publications and ensuring that the works of its collections gain international visibility and recognition through collaborations with other institutions and museums in Greece and abroad.

The museum actively supports research and welcomes scholars and students interested in the historical avant-garde in Eastern Europe, Russia, Ukraine, the Baltics, the Caucasus, and Central Asia, its connections with avant-garde movements in Europe, and its continuing relevance to contemporary artistic practices and experimentation.

Since 2027, the Bowlt & Misler Library and Research Center has been operating at MOMUS, featuring a specialized library that includes more than 40,000 specialized books from the late 19th century to the present. The collection focuses on the history of culture and art in the Russian Empire, the Soviet Union, Eastern Europe, the Caucasus, and Central Asia.