Resilience to threats posed by foreign intelligence services is one of the national security priorities enshrined in the Law on National Security Framework of the Republic of Lithuania. It declares that the state authorities must protect Lithuania from subversive activities of foreign secret services and their cover structures and prevent them from using the territory of the Republic of Lithuania or as a transit state for subversive activities against other states. Hostile activities by foreign intelligence and security services pose a serious threat to the national security of small states. This threat has recently intensified. The activities of foreign intelligence and security services are not limited to the gathering of national, NATO, and European Union classified and other information through hijacking, extortion, or other means. Intelligence and security services in foreign countries are actively engaged in cyber, information, influence, and other hybrid attacks, organising and carrying out diversions, and assassinating foreign and domestic citizens who threaten their political leadership. Therefore, strengthening the resilience of small states by enhancing the capacity of their intelligence and counterintelligence institutions, citizens’ awareness, critical thinking, and resilience to the unlawful influence of foreign intelligence and security services is crucial to reduce the threat posed by foreign intelligence and security services. This chapter examines Lithuania’s best practices in ensuring the resilience of the state and society against espionage and other subversive threats posed by foreign intelligence services.