Since its foundation, the Polish Academy of Arts and Sciences has been actively involved in cooperation with foreign institutions and activities on the international forum. Already in the 19th century the Academy initiated archival expeditions to study sources for the history of Poland (among others the so­called Roman Expedition to Vatican Archives connected with it’s opening in 1881), and sent its representatives to international congresses. In 1893, the Academy of Arts and Sciences became the owner of the Polish Library in Paris, and opened a scientific station there. The Academy’s library in Cracow carried on a broad exchange of publications from the very beginning. In 1921, the PAU became a founding member of the Union Académique Internationale (UAI).

After its activities were resumed, the PAU’s membership in the UAI was renewed in 1993, and the PAU began to take part in the research and publication programs of this organization. The publication of the Polish series of the Corpus Vasorum Antiquorum (CVA) was completed with volume 10, devoted to Cypriot pottery from the collection of the National Museum in Warsaw; has been published a Cracow sheet in the Tabula Imperii Romani (TIR), and material prepared for sheet 12 of the Atlas du Monde Grec et Romain (UAI Project XLVIII). The edition of a Polish series in the Corpus Antiquitatum Americanensium (CAA) has been commenced, and the first two volumes have already been published, devoted to the ceramics and Peruvian textiles in the collection of the Cracow Archaeological Museum (the Kluger Collection, formerly the property of the PAU). After preparing and issuing the pre-columbian monuments of Polish collections, the inventories edition of sites disovered during research works in Peru rivers valleys by Polish missions have started. The first volume - being printed - presents sites in the Huaura river valley. The decision has also been made to issue a Polish series in the Syllogae Nummorum Graecorum (SNG), the first volume of which is devoted to the collection of Greek coins at the Łódź Archaeological Museum. The second volume - being printed - is dedicated to coin collections of Greek colonies of the Black Sea area from the Cracovian National Museum collection. The works are undergoing concerning edition of further collections - of Łódź and Warsaw museums. PAU members are also participating in the realization of such projects as the Corpus Philosophorum Medii Aevi (Project IX) and Civilisations de 1\\\'Asie Centrale (Project XXV). The PAU is participating in new UAI projects, including, among others, the Magna Moravia project, which involves developing a corpus of archaeological, historical, and linguistic sources for the history of the Greater Moravian state. So far monographies of archaeological sites from the period of the Greater Moravian state explored in Southern Poland have been published (i.e. an early Medieval stronghold in Naszacowice).

Thanks to the effective cooperation of the PAU and the UAI, the annual plenary meeting of the UAI (involving representatives from 44 academies around the world assembled in the UAI) took place in Cracow in 1999, during which the PAU’s representative, Janusz K. Kozłowski, was elected an officer of the UAI. Since 2002 professor Kozłowski represents UAI in the CIPSH-UNESCO as a Vice President.

PAU is also the ALLEA (All European Academies) member. It is the association of all european Academies of Arts and Sciences. In 2006 the VIIth General Assembly of ALLEA took place in Cracow, organised by PAU and PAN.
PAU takes a very active part in ALLEA initiatives concerning intellectual property protection, scientific information flow, scientific associations role in united Europe. One of PAU delegates participate in ALLEA Commission evaluationg European Science Foundation works in the field of humanistic and social sciences.

The Polish Academy of Arts and Sciences is a funding member of Centro Interuniversitario (International Interuniversity Centre for the Mediterranean, Central and Eastern Europe and Eurasia (the area of Russia and the Ottoman Empire)) represented by the Lublin Catholic University, the Tallin University, the Szeged University, the La Sapienza University, the LUMSA University, the Lecce University, the Angers University, the Louvain-la-Neuve University and PAU whose Secretary General is a President of General Assembly of the Centro.

A contract has been signed with the Slovak Academy of Sciences. This has borne fruit not only in the exchange of personnel, but also in the realization of joint research in the areas of linguistics, archaeology, history, ethnology, and art history. Field research is being conducted, including investigations of archaeological sites in eastern and southwestern Slovakia. The first results have been summarized in last volumes of Transactions of the Commission on the Prehistory of the Carpathians: The Early Linear Pottery Culture in Eastern Slovakia and Archaeology and Natural Background of the Lower Beskid Mountains, Carpathians.

Cooperation was also initiated, and a contract signed (1998) with the Academy of Sciences of the Czech Republic, and with the Slovenian Academy of Sciences (1998). The decision was made to enter into cooperation with the Saxonian Academy of Sciences in a joint research project on the so­called Vendian toponomastics in eastern Germany. Together with the Universities in Lipsk and in Wrocław PAU issues annual Onomastica Slavo-Germanica. Somewhat looser forms of cooperation exist between the PAU and the Austrian Academy of Sciences, as well as the Brandenburg Academy of Sciences in Berlin. Finally, we have signed a scientific cooperation agreement with the Royal Flemish Academy of Sciences, Letters, and Fine Arts in Belgium. The PAU has also been engaged in scientific cooperation on the basis of treaties negotiated by the Polish Ministry of Foreign Affairs with several countries, including France, Italy, the Czech Republic, Macedonia, and Egypt.

In 2003 a contract was signed with the Hungarian Academy of Sciences. Acordingly with the agreement some subjects were accepted for realization as jointly conducted search works. As for 2006 further search works have been planned to be conducted at the open palaeolitical sites in Eger area.

In 1994, the PAU Scientific Station in New York was founded, based on the Polish Institute of Arts and Sciences in America (PIASA), which continued the PAU’s traditions during the Second World War and the period of compulsory suspension of PAU activities, from 1952 until 1989.

Contacts have been established with the Polish Institute of Arts and Sciences in Canada, founded in 1943 as a branch of the Polish Institute in New York, and since 1976 operating as an independent Canadian organization at the Mc Gill University. Some subjects of medicine and archaeology have been selected to be continued together with the Mc Gill University in Montreal.

The PAU took over the program of the Polish Historical Institute in Rome, financed by the Lanckoroński Foundation.
This program concerns publication of the \\\'Acts of the Apostolic Nunciate in Poland\\\' and is not limited in time.

In 2001 an agreement was signed with the La Sapienza University in Rome about the scientific co-operation. As far as now, it concerns the fields of history and archeology, but accordingly with the needs it might be broadened into another disciplines. Similar agreement was also signed with the University in Lecce in 2003.

Harking back to an older tradition, the PAU is also co­organizing archaeological investigations in Ukraine, continuing the excavation of a large Scythian barrow in Ryzhanovka, among other projects. These investigations have brought one of the most outstanding archaeological discoveries of recent years: the discovery of the richly accoutered burial of a Scythian ruler. Together with the Lwow center archaeological research works are being conducted at the Upper Dniester basin. bringing out significant results as to our knowledge concerning the neolithic and the Bronze Age period\\\'s settlements. Lately signed (in March 2006) co-operation agreement with the National Academy of Sciences of Ukraine will support the existing co-operation and will broaden its range to new disciplines, especially history (archive search queries) and the Quaternary period geology (there is a plan of new research works in Starunia where some examples of the Pleistocene fauna have been found).

Returning to its pre­war intentions, the PAU has also contributed to archaeological research being conducted in Greece. These investigations have dealt with the sequence of layers, unique in this part of Europe, in Cave No. 1 at Klisura (eastern Peloponnese), in which there occur traces of habitation and palaeontological finds from the period of the last Ice Age.
This research is contributing to our understanding not only of the evolution of culture in Greece, but also of climatic and palaeoecological changes over the last 100,000 years.

Since 2003 a research program of the Ministry of Science has been continued concerning the role of Greek islands in contacts by sea between the East and Europe. Research on the Giaur Island (Sporades) and the Kythnos Island (Cyclades) enabled a discovery of the Mesolithic settlements from the period of the end of 10th to 8th century B.C. At the Maroulas center on the Kythnos Island some traces of the Middle East style stone architecture have been discovered. At the same time domesticated livestock remains proves the role of sea contacts in appearing the neolithical production industry in the South-East Europe.

Polish Academy of Arts and Sciences have also supported research conducted by the Institute of Archaeology of the Jagiellonian University in the Nile Delta, within the frame of the cultural co-operation agreement between Poland and Egipt.