Thus, education boosts civic engagement sharply, and educational levels have risen massively. Unfortunately, these two undeniable facts only deepen our central mystery. By itself, the rise in educational levels should have increased social capital during the last 20 years by 15-20%, even assuming that the effects of education were merely linear. (Taking account of the curvilinear effect in Figure 1,the rise in trusting and joining should have been even greater, as Americans moved up the accelerating curve.) By contrast, however,the actual GSS figures show a net decline since the early 1970s of roughly the same magnitude (trust by about 20-25%, memberships by about 15-20%). The relative declines in social capital are similar within each educational categoryroughly 25% in group memberships and roughly 30% in social trust since the early 1970s, and probably even more since the early 1960s.