This chapter examines the effects of electoral system on the policy preference and behavior of politicians in South Korea. Korea is an ideal test bed for this analysis because it has a mixed-member electoral system. About 75% of representatives in the National Assembly are elected through the single-member-district (SMD) system, while the remainder are elected through proportional representation (PR). This allows us to identify different policy preferences and behaviors between two groups of separately elected officials. The main finding is that SMD representatives have more incentives than PR members to supply geographically targeted goods rather than nationwide public goods such as social welfare. Also, we observe a similar tendency for standing committee membership. Standing committees, which are instrumental to supplying geographically targeted benefits, are filled with SMD members, whereas most PR representatives are members of standing committees that oversee the government ministries in charge of social affairs.