Is double citizenship possible in Estonia?

Legally speaking the answer is NO but there are situations where a person can have Estonian citizenship and also citizenship to another country.

Our law states that a citizenship obtained by birth cannot be taken away. Commonly the situation has arisen in connection to our so-called "first republic" that existed during 1918-1940 (the independence was again restored in 1991). If an Estonian citizen left Estonia during that time and had children later in another country then those children would by Estonian citizens by birth and this right cannot be taken away.

To pursue the option of obtaining the citizenship back one must prove the connection of their parents or parent to Estonia and that they were citizens. This is usually done using also the data in the national archives and for example a person can order research to be done on their case using this website:

https://www.ra.ee/vau/index.php/en/enquiry/application/create?type=5