Why have separatist sentiments increased in Hong Kong despite of China’s growing economic attractiveness? This question is critical for China–Hong Kong relations. However, few studies have explored it from a comparative perspective. This study compares Hong Kong and mainland college students’ national identities by making a series of interlocked surveys and interviews from 2012 to 2016. It shows that Hong Kong students have a much lower sociopolitical identity with China, which proves to be the primary cause for their separatist tendencies. Although they hold a comparably strong pan-Chinese economic identity, it does not strengthen their sociopolitical identity as it does for mainland students. This can be attributed to their post-materiali...