Background: Two vaccines against human papillomavirus (HPV), a necessary cause of cervical cancer, are currently licensed and recommended for routine administration in the U.S. to girls in a three-dose series. Purpose: This study examined effects of race/ethnicity, poverty, and year on completion of the three-dose HPV vaccine series among those who initiated vaccination. Methods: Data from the 2008–2009 National Immunization Survey-Teen for girls aged 13–17 years who received at least one dose of HPV vaccine (n_7606) were analyzed in 2010–2011 using logistic regression to adjust for covariates including measures of access to care. Results: During this 2-year period, 55% of adolescent girls who initiated vaccination completed the three-dose series. Completion was signifıcantly higher in 2009 (60%) compared to 2008 (48%; p_0.001). After controlling for covariates, adolescents who were black (AOR_0.48, 95% CI_0.40, 0.57) or Hispanic (AOR_0.75, 95% CI_0.64, 0.88) were signifıcantly less likely to complete vaccination than whites. Adolescents living below the federal poverty level were signifıcantly less likely to complete vaccination than adolescents with household incomes _$75,000 (AOR_0.76, 95% CI_0.63, 0.92). There was no signifıcant interaction between race/ethnicity and year (p_0.92). Although poverty was associated with lower completion rates in 2008, this association was not observed in 2009 (p_0.05 for poverty–year interaction). Conclusions: HPV vaccination completion rates increased between 2008 and 2009. However, signifıcant differences by race/ethnicity and poverty were observed, and the racial/ethnic differences persisted.