One fundamental question in syntax is how to understand the observed universality and diversity of syntactic structures across different languages. This paper addresses this question by focusing on yes-no question formation in two Chinese dialects spoken in Wuhu and Nanjing. Based on novel data and diagnostics, which involve a systematic comparison of the formal properties of different types of yes-no questions in Wuhu and Nanjing, this paper proposes a uniform analysis to account for both the uniformity and variation of Wuhu and Nanjing yes-no questions. This proposal improves on existing approaches to yes-no question formation by distinguishing between clause-internal question particles and A-not-A strings, and showing that what undergoes movement in Wuhu and Nanjing yes-no questions is the question operator instead of the polarity variable.