China's rates of internal migration increased to an all-time high of over 200 million individuals at the beginning of the twenty-first century. Yet, there is a dearth of information on the lives of young migrant populations. The aim of this study was to explore how migration influences the sexual attitudes and behaviours of 18-24-year-old migrant men and women in Shanghai, China. A total of 64 migrants participated in 10 focus-group discussions and 20 in-depth interviews. Guided by acculturation theory, coded data were organised into analytic matrices to compare themes across participants. Factors associated with increased sexual-risk behaviours include acculturative stress, discrimination leading to social isolation, conflicts between traditional and modern city values and increased sexual opportunities. Premarital sex, cohabitation, unprotected sex and visiting sex workers are common among this population. Reasons for not using condoms included being unprepared, lack of knowledge and barriers in accessing reproductive services due to not having urban documentation. Local family planning programmes should help migrants negotiate traditional and modern values and partner with work-sites to provide comprehensive sexual education and services and train health professionals in the specific healthcare needs of young migrant populations.