BACKGROUND AND OBJECTIVES: Although mortality rates are highest for infants of teens aged 15 to 19, no studies have examined the long-term trends by race and ethnicity, urbanicity, or maternal age. The objectives of this study were to examine trends and differences in mortality for infants of teens by race and ethnicity and urbanicity from 1996 to 2019 and estimate the contribution of changes in the maternal age distribution and maternal age-specific (infant) mortality rates (ASMRs) to differences in infant deaths in 1996 and 2019. METHODS: We used 1996 to 2019 period-linked birth and infant death data from the United States to assess biennial mortality rates per 1000 live births. Pairwise comparisons of rates were conducted using z test statistics and Joinpoint Regression was used to examine trends. Kitagawa decomposition analysis was used to estimate the proportion of change in infant deaths because of changes in the maternal age distribution and ASMRs. RESULTS: From 1996 to 2019, the mortality rate for infants of teens declined 16.7%, from 10.30 deaths per 1000 live births to 8.58. The decline was significant across racial and ethnic and urbanization subgroups; however, within rural counties, mortality rates did not change significantly for infants of Black or Hispanic teens. Changes in ASMRs accounted for 93.3% of the difference between 1996 and 2019 infant mortality rates, whereas changes in the maternal age distribution accounted for 6.7%. CONCLUSIONS: Additional research into the contextual factors in rural counties that are driving the lack of progress for infants of Black and Hispanic teens may help inform efforts to advance health equity.