Many of planners and researchers argue that social mixing could contribute to sustainable communities, but some people still more likely to live in homogeneous community than diverse one. Understanding resident perception and preference toward socially mixed neighborhood therefore would be necessary process to promote sustainable community development. This study addresses the perception and willingness-to-accept living in socially mixed communities in Korea, with an emphasis on income-mix. This study conducted a survey that contains three main questionnaires: (1) personal characteristics and neighborhood attributes, (2) comfortability to a various level of mixed income communities, and (3) willingness-to-move in these mixed income neighborhoods. The survey was conducted in 2018 for seven metropolitan cities in Korea, including Seoul, with 2,000 respondents. The results showed that the willingness-to-accept mixed income communities varies depending on the socio-economic and demographic background of respondents, implying that a more systematic community development strategy is required to achieve social-mixing