The collapse of the former Soviet Union, drew the Caspian Sea region out from a pure and calm strategic region and created numerous geopolitical opportunities and challenges for Iran and Russia. This fundamental development caused change in the surrounding Caspian Sea’s political borders and impacted on the legal status of the sea. Iran and Russia’s policies and approaches towards the Caspian Sea legal status fundamentally altered, as well. At the same time, with the emergence of differences of opinions and views among the coastal countries on the legal status and the way to exploit the Caspian Sea resources, there was created a fertile bed for presence and interference of big and extra-regional countries in the Caspian Sea. Under such circumstances, Iran/Russia policy alignment for managing the legal status developments of the Caspian Sea and preventing it from becoming a new hotbed of tensions , as well as, nearing together the opinions and positions of the other coastal countries has been crucial. The pivotal and main question of the present article is what impact Iran and Russia policies toward the legal status of the Caspian Sea can have on the expansion of penta-lateral cooperation among the Caspian Sea coastal countries. In the present paper this question is put to test whether Iran/Russia policies towards the Caspian Sea legal system- apart from the negative historical mindsets between the two countries- due to reasons like geographical continuity, regional requirements, joint destiny and the Caspian Sea vulnerability resulting from presence of the big powers, and concerns about emergence of instability and insecurity in the Caspian Sea, have been more convergent and led to strengthening of cooperation and conclusion of various documents of penta-lateral cooperation among the coastal countries. The present paper is of the Analytical-Descriptive type and the method used is inferential and the data has been analyzed using library and Internet sources.