The article provides the information on Lithuania’s military contribution to the assurance of international security and stability – the participation of the military personnel of the Republic of Lithuania (further – RL) in international operations and training missions of the European Union in 2004–2017. The study briefly familiarizes the reader with legal principles of participating in international operations and presents essential restrictions affecting the number of military personnel participating in international operations. The author of the article thoroughly analyses the change in the number of troops of the Lithuanian Armed Forces in international operations conducted by NATO, the European Union, the United Nations, and other strategic partners in 2004–2017. The military contribution of Lithuania is provided within the context of joint military operations carried out by NATO, the EU, and the UN, the tendencies of the change in the participation of the Lithuanian military personnel in international operations are presented as well. Keeping in mind the change in the resources (financial and human) allocated and available to the National Defence System of the RL and the political will to participate in international operations, expressed by the Seimas of the RL, the author attempts to find out, on the grounds of historical perspective, their potential connection with and influence on the Lithuanian military contribution to future international operations.