The present study looks at how the Northwest Youth were politically excluded under the Rhee regime, resurrected under the Park Chung Hee regime, and how they became a major political force in today's Korea. The results of the study are as follows. The Northwest Youth League had an organic relationship with the Northwestern Christian Refugees, including the Northwest Student Confederation and Han Gyeong-jik. So their historical identity is linked to the lineage of nationalist leaders Ahn Chang-ho, Lee Seung-hun, and Jo Man-sik. The Northwest Youth Club played a key role in the establishment of the Syngman Rhee regime, onto which they pinned their hopes. Their first action was creating branch groups to solidify their power. Their main activities targeted North Korea, and they also carried out left-wing sweep activities. Actions in North Korea consisted mainly of intelligence and propaganda. Their espionage activities were supported by the U.S. counter-intelligence corps. Left-wing sweeps were executed through military activities, schools, and local dispatch. Aiming at the National Guard(조선경비대), a number of Northwest Youth enrolled in the National Guard Officer Academy's 5th, 7th, and 8th class for purposes of surveillance. This was followed by left-wing sweeps via area dispatches. The most typical example of these sweeps was the Jeju 4ㆍ3. Incident. The Northwest Youth League played an important role in Rhee's parliamentary election and presidential inauguration, but the group was dissolved after 2 years. Then the Korea War broke out, and they thought they had a chance of recovering. They tried to re-organize the Northwest Youth but were disbanded due to Rhee's opposition. Seon-u Gi- seong, the former Northwest Youth Chair, received several requests from the UN to form an organization, and Klim Seong-ju, who had been the Northwest Youth director, was appointed Pyeongnam governor by the UN military government. Rhee was displeased by these independent actions. Eventually, Kim was charged with involvement in a murder plot aimed at Rhee and was sentenced to death. When the Northwest Youth Movement deployed a rescue operation to save Kim's life, the organization was completely dissolved. But the Northwest Youth League revived after Park Chung Hee's military coup. The Northwest Youth who had entered the National Guard Officer Academy's 5th and 8th class at the time of the League formation, were major players in the coup. When the Park administration took power many intellectuals joined hands with Park and among these were many Northwest Youth League members. The 7th class played a vital role in the Park regime through participation in the Vietnam War. The 8th class were mostly employed in Army intelligence agency, and after the coup some of them became founding members of the Central Intelligence Agency. They became the movers and shakers of Korean society. Many Northwest Youth League members who had undertaken counter- intelligence activities before the Korean War moved horizontally to Army intelligence in February, 1954. The Army intelligence agency employed many League members, who were anti-communist through-and-through and possessed hands-on wartime experience. Seon-u Gi-seong, a leading figure in the League, organized the Young Friends League (Cheonguhoe, 靑友會) and carried out projects like the building of an anti-communist youth movement monument (building of the Anti-communist Youth Movement Monument), through which they recruited many new members. They also were active as a private organization (civic organization) supporting Park's anti-communist policies. In short, the Northwest Youth League, in conjunction with the Park regime, played (can be said to have played) a pivotal role in the modernization of Korea.