Feminist scholars have argued that husband gender traditionalism is one of the root causes of spousal violence against women. Using couple-level data from Hong Kong (N = 871 couples), this article argues that a second mechanism—couple gender value mismatch—also explains husband-to-wife physical assault. Our findings show that a husband’s gender traditionalism is positively associated with husband-to-wife physical assault only when the husband is coupled with a wife who has non-traditional gender attitudes. Similarly, egalitarian gender attitudes in wives are positively associated with husband-to-wife physical assault only when a non-traditional wife is coupled with a traditional husband.