The Health Insurance Portability and Accountability Act of 1996 requires Notices of Privacy Practices (NPP) in plain (clear, concise, and easily understood) language. The objectives of this study were to test the readability of U.S. dental school NPPs; examine factors relating to readability; and develop a plain language NPP supplement. Readability statistics were Flesch Reading Ease (FRE) and Flesch-Kincaid Grade Level (FKGL). Social capital measures of potential resources available to people in a civil society (e.g., perceived trust, perceived reciprocity, and per capita voluntary organization membership) along with lawyers per capita for each state were examined for potential relationships with readability levels. One-sample t-tests assessed plain language (FRE=60, FKGL=8), and analyses of variance compared groups. Spearman rank correlations (r(s)) compared social capital to readability. A plain language NPP supplement was developed. All fifty-six U.S. dental school NPPs were obtained (100 percent response). Forty-eight of fifty-six schools (86 percent) had website NPPs. FRE and FKGL were significantly more complex than plain language, overall (both p<0.0001, 95% CIs: FRE=37.6, 40.5; FKGL=11.2, 11.8) and by region (all p<0.014). Readability did not differ by region. Social capital measures moderately related to readability (0.18 < or = |r(s)| < or =0.39) with reciprocity being most related (FRE r(s)=0.36, FKGL r(s)=-0.39). U.S. dental school NPPs are more complex than "plain language."