This chapter examines the prejudice and discrimination that Mainland Chinese immigrants on the One Way Permit (OWP) scheme often face integrating into Hong Kong society. It discusses the implications of anti-immigrant sentiment towards Mainland Chinese immigrants, particularly for the political and economic future between Hong Kong and Mainland China. The implications of anti-immigrant sentiment are profound and pose widespread implications for policy makers in Hong Kong and most importantly for relations between the Mainland Chinese and the Hong Kong Special Administrative Region government. The chapter investigates the social and economic integration problems that migrants on the OWP scheme face. It provides an overview of the historical developments and immigration policies that have underpinned immigration policy. The chapter argues that the Petersen ethnic conflict model has more explanatory power than both the classic ethnic competition and the social identity models combined, in explaining why Hong Kong citizens tend to hold anti-immigrant sentiment towards Mainland Chinese immigrants.