Background: Relatively little is known and inconclusive about social inequality in human papillomavirus (HPV) vaccination among teenagers in the United States. This study aims to investigate whether there is a social disparity in HPV vaccination among teenagers and if so, whether it can differ by the source of teen vaccination information (parental reports and provider records). 
Methods: We used the data from the 2019 National Immunization Survey-Teen (NIS-Teen; 42,668 teenagers, aged 13-17) including parental reported vaccination status. Among them, 18,877 teenagers had adequate provider reported vaccination records. Two socioeconomic status (SES) measures were used: mother’s education and annual family income. Multivariate logistic analyses were conducted. 
Results: False negatives of parental reports against provider records were more than two times higher (p < 0.001) in low SES teens than in high SES teens. In both SES measures, the proportion of HPV unvaccinated teenagers were lowest in the highest SES level in analyses with parental reports. However, it was the opposite in analyses with provider records. Interestingly, regardless of vaccination information source, the HPV unvaccinated rate was highest in the middle SES teens (>12 years, non-college graduates; and above poverty level, but not > $75K). 
Conclusion: A significant social inequality in HPV vaccination among teenagers exists in the United States. The pattern of social inequality in HPV vaccination can be distorted when only parent reported vaccination information is used.