In 1918-1939, intensive intelligence reconnaissance in the Second Republic was carried out not only by the special services of Germany and the Soviet Union but also by the Intelligence of the Lithuanian Republic. With a decidedly smaller financial and personnel potential at their disposal, the Lithuanians were capable of successfully recognising the political and military situation in the Polish state during the titular period. The article casts further light on the operational methods applied by Lithuanian special services engaged in espionage. Prime emphasis has been placed upon the recruitment of openly anti-Polish citizens of the Second Republic among the Lithuanian minority, attempts at hermetically isolating this community for the purposes of reducing the potential identification of agents and informers, as well as on the deployment of soldiers together with junior and senior officers of the Polish Armed Forces in order to obtain necessary information. A prominent element of such undertakings was the recruitment of whole families, which comprised widespread networks whose every member was entrusted with a concrete task. The specific nature of international relations during the entire discussed period facilitated well-developed smuggling which made it possible to run the couriers and agents of both sides. In the first half of the 1920s an essential part was played by a partisan movement organised both by the Poles and the Lithuanians. The question of Wilno (Vilnius) and the Wilno district, not regulated by diplomatic measures, stirred further emotions and reinforced antagonism. Lithuanian calls for an armed occupation of Wilno were supported by the success of the Memel uprising and that town's annexation by the Republic of Lithuania, opening a path towards the creation of partisan detachments subsidised by the Lithuanian government in order to harass Polish military and police authorities in former Central Lithuania. Soon, this idea was abandoned and a majority of the former partisans joined the ranks of Lithuanian Intelligence agents.