The world is rapidly becoming more educated at higher education level. In nearly all countries with per capita GDP of more than about $5,000 per annum there is a longterm tendency to growth of participation. The worldwide Gross Tertiary Enrollment Ratio (GTER) increased from 10% in 1972 to 32% in 2012, and is now rising by 1% a year. By 2012 the GTER had reached 50% in 54 national systems, compared to 5 systems twenty years before, and there were 14 countries with a GTER of 75% or more. The tendency to high participation systems (HPS) is common to countries that vary widely in rates of economic growth, education system structures, and financing arrangements, but share the tendency to urbanization. Possible causes include state policies, economic development, aspirations for social position, credentialism, global factors, and combinations of these. The paper describes the tendency to HPS, explores the possible explanations, and begins to reflect on the implications; on the way reviewing prior discussions of growth in participation including Trow (1974), Schofer and Meyer (2005), and Baker (2011). It closes with suggestions for further investigation.