This study extends Trow's theory of higher education development to examine changes in national-level tertiary education graduation rates. Applying Trow's framework we arrive at three stages: (1) elite systems with gross tertiary graduation rates less than 15%, (2) massified systems with gross tertiary graduation rates between 15% and 50%, and (3) universal systems with gross tertiary graduation rates above 50%. This study conducts event history analyses using a unique cross-national panel dataset, which spans the time period from 1999-2005. Following the work of Berry and Berry, our event history analyses model both the internal features of each country and the influence that nation-states have on each other with regard to setting tertiary education graduation policy. We find significant influences of both internal determinants and diffusion factors. We find a positive, significant effect of membership in the OECD consistent across both the massified and universal thresholds. We also find a positive, significant effect of having a more stable political system for crossing the 15% threshold. In addition, being located near a pioneering nation, the UK, has a positive, significant effect of crossing the 50% threshold. (Contains 3 tables, 4 figures, and 13 notes.)