The number of mainland Chinese students was 791 (64% of total international students in Hong Kong) in 1996/97 whereas such number went up to 12,037 (73%) in 2016/17—more than fifteenfold increase within 20 years. In particular, mainland China undergraduates (MCU) exhibited a phenomenal growth from 5 in 1996/97 to 6,852 in 2016/17. Nonetheless, few studies have focused on this group of students concerning their acculturative stress and/or mental health in Hong Kong, even though there were several cases of suicide committed by MCU in Hong Kong in the past decade. Completing tertiary education in one’s home country is generally not an easy task, and pursuing a university degree in a culturally different and unfamiliar place will surely add to one’s difficulties. A literature search of scales assessing acculturative stress showed that none of the existent scales were applicable to MCU in Hong Kong, either because of language issues, different target population, or cross-cultural problems. Hence, the purpose of this study was to develop and validate a suitable scale to measure the acculturative stress of MCU in Hong Kong.A 172-item pool was created from literature, in-depth and focus group interviews, and then validated in a sample of 274 MCU in Hong Kong using one-parameter Rasch model analysis to produce a 117-item Acculturative Stress Scale for Mainland Chinese Undergraduate Students (ASSMCUS) in 21 dimensions, which are English Barrier: Limited English Proficiency; English Barrier: Limited Colloquial English; Cantonese Barrier: Limited Cantonese Proficiency; Cantonese Barrier: Limited Colloquial Cantonese; Study Stress: Heavy Course Load; Study Stress: Student-Centred Learning Approach; Cultural Difference: Mutual Cultural Misunderstanding; Cultural Difference: Identifying with Hong Kong’s Culture and Values; Social Interaction: Loneliness; Social Interaction: Hard to Make Friends with Hong Kong People; Social Interaction: Limited Social Connectedness; Discrimination:
