Over the past 40 years, global tertiary expansion has been driven in part by the rise of the non-university sector. The growth of this sector, which includes vocational colleges, also contributes to increasingly diverse national higher education systems. Prior research has focused on inter-state variation in national systems, while very few studies have explored intra-state variation in the expansion of non-university sector. Building on the policy innovation and diffusion model, this study uses event history analysis to investigate key drivers behind Chinese prefecture cities' adoption of vocational colleges during the latest tertiary education expansion. The study employs a rich panel dataset from 273 Chinese cities between 2000 and 2014. Findings suggest that the socioeconomic and the politico-institutional contexts matter the most for cities' policy adoption, and the influence of policy diffusion is negative but not significant. Moreover, there is substantial heterogeneity across time and region. The characteristics of early adopters significantly differ from those of late adopters, and the diffusion paths vary within and across regions. This study illustrates that the emergence of sub-national government affiliated non-university institutions is driven by a complex combination of socioeconomic, politico-institutional, and policy forces. Results highlight the regional contextual factors that may override coercive pressure from national strategies to promote the non-university sector expansion and the structural diversity in the context of less developed economies.