Using the comparative case study (CCS) method, this article compares the findings from a longitudinal ethnographic research project of rural children in Northwest China (2005-2012) and a second longitudinal study of migrant children in eastern China (2015-2019). It examines rural and migrant students' and educators' (re)interpretations and uses of "suzhi" (quality) and "suzhi" education in the context of rapid urbanization, various locations in between the city and the countryside, and how these usages problematize and challenge the rural-urban dualism embedded in the existing literature on rural and migrant children in China. These two studies explore how "suzhi" means different things for different stakeholders across time and place in both formal discourses, such as the curriculum, and in informal discourses, as seen in what educators and students value and practice. The article enriches theories on "suzhi" by showing how it: 1) reflects both the rural-urban gap and social stratification in China; and 2) reveals the shifting paradigm of "suzhi" education specifically and of education in China more broadly. The article also showcases how the CCS approach can be used to disrupt taken-for-granted categories and dichotomies, such as the urban-rural dualism, by closely examining concepts like "suzhi" across place, time, and with different groups of children.