Data from the distant past are fertile ground for testing social science theories of education and social mobility. In this study, we construct a dataset from 3,640 tomb epitaphs of males in China’s Tang Dynasty (618–907 CE), which contain granular and extensive information about the ancestral origins, family background, and career histories of the deceased elites. Our statistical analysis of the complete profiles yields evidence of the transition away from an aristocratic society in three key trends: 1) family pedigree (i.e., aristocracy) mattered less for career achievement over time, 2) passing the Imperial Examination ( Keju ) became an increasingly important predictor of one’s career achievement, and 3) father’s position always mattered throughout the Tang, especially for men who did not pass the Keju . The twilight of medieval Chinese aristocracy, according to the data, began in as early as the mid-seventh century CE. Data from excavated tomb epitaphs of male elites in China’s Tang Dynasty (618-907 CE), reveal patterns of education and mobility very much like contemporary patterns. After 650 CE, China’s Imperial Examination System ( Keju ) shaped social mobility in the medieval bureaucracy much as university education shapes mobility in rich countries today. Early in the Tang Dynasty, aristocratic ancestry was a distinct advantage, but over time, exam results overtook aristocracy. The fall of family ties and rise of credentials is relevant to historians’ debates on the fate of China’s medieval aristocracy. Furthermore, passing the exam may have even equalized chances of subsequent success, as father’s occupation was not a factor in the occupational rank of men who passed the Keju . The Tang Dynasty is intrinsically interesting due to its antiquity, of course, but it is relevant for our agenda because it was the only long-lived Chinese dynasty where competitive exams for entrance into the bureaucracy coincided with a significant presence of aristocratic clans in politics. Prior to the Tang, the ruling class controlled entry into the imperial bureaucracy through institutionalized patronage, based on recommendation, direct nomination, or pedigree-based allocation. With the Chinese Government Employees Dataset-Qing (CGED-Q), researchers can now link records of over 300,000 government officials in China’s late Qing Dynasty (1830–1912) and the corresponding Keju records, along with other information, to further investigate questions concerning historical mobility and social stratification in the last century of imperial China ( 21 ). In this paper, we employ quantitative social science methodology that allows for controlling for various confounders and Substantively, the significance of the Tang is history: the Tang data are from the seventh through ninth centuries. We therefore extend social mobility studies even to medieval times, when an aristocracy was very much in power and competitive exams still developing. Furthermore, our estimates of the relative roles that Keju and various dimensions of family background played in Tang China could bridge across this interdisciplinary scholarship on social mobility and Keju in late imperial China, and the separate medieval Chinese aristocracy literature that dovetails with the prominent “Tang-Song Transition Thesis.” We briefly discuss the latter literature in the penultimate section. Results obtained from Model 2 reveal how profoundly Chinese social structure changed after 690. The aristocracy no longer dominated, as prominent branch status no longer improved an individual’s position in the bureaucratic system. Class advantage did not disappear altogether as each point of father’s status raised his son’s status by 0.27 point as before, but that one-generation advantage was no longer compounded by the legacy of many generations. As lineage mattered less, performance mattered more. Passing the competitive exams could, after 690, land a man into office at least one full rank higher than that achieved by an otherwise comparable man who had not passed the exam. The coefficient for the interaction between prominent branch and Keju was not but that did not matter because the main effect of prominent branch was near zero in all models. The marginal effect of father’s position was 0.28 for men who did not pass the Keju but a statistically insignificant 0.08 for those who passed it. The Keju could have just been a novel status symbol or legitimization of already existing privilege. If so, then a statistical analysis could predict exam success accurately from data on prominent branch membership and ancestors’ statuses. But it was not so. The Lower panel of Table 2 shows that neither prominent branch nor father’s rank predicted exam success. Conclusions and Discussion This study constructed a unique dataset containing information from 3,640 tomb epitaphs of male elites in China’s Tang Dynasty (618–907 CE). Epitaphs contain granular information about the ancestral origins, family background, and extensive career history written for these deceased individuals. Our statistical models reveal how Chinese aristocracy disappeared as a factor in men’s careers while the imperial exam ( Keju ) became a major factor in elite selection. Results lend support to hypotheses based on sociological theories of intergenerational mobility ( 5 , 10 ). Specifically, men’s status in the hierarchy of medieval China came to depend more on their own achievements and less on the status of their family of origin. Blau and Duncan’s conclusion about the United States in 1962 applied to Tang China a millennium before: “...superior status cannot any more be directly inherited but must be legitimated by actual achievements that are socially acknowledged” ( 2 , p. 430). Our results extend the social science of intergenerational mobility to medieval times. They also help move the historical literature forward from a longstanding debate on how society changed in the Tang Dynasty.