As under-5 mortality declines globally, newborn or neonatal mortality is becoming increasingly important. Depending on measurement and empirical data sources, calculation of the magnitude and trend of all-cause and cause-specific neonatal mortality ranges from direct methods to model-based estimates. From 1990 to 2019, the global neonatal mortality rate decreased by 52%, though wide regional variations persist, with sub-Saharan Africa (SSA) consistently experiencing the highest neonatal mortality rates, followed by Southern Asia, accounting for 79% of the 2.4 million total newborn deaths in 2019. Globally, most deaths in 2019 are due to preterm birth complications (36%), intrapartum-related events (24%), congenital abnormalities (10%), pneumonia (8%), and sepsis (7%). Since 2000, in low- and middle-income regions like Central Asia and South Asia and SSA, most deaths were avoided through declines in intrapartum-related events (3.4% and 1.9% AARR [average annual rate of reduction from 2000 to 2019], respectively) and preterm birth complications (2.9% and 1.9% AARR, respectively); whereas high-income regions like Europe, Northern America, Eastern Asia and South-Eastern Asia were more rapidly able to reduce deaths due to congenital abnormalities (2.8% and 3.2% AARR, respectively). More investment is urgently required to improve data collection and data quality, as well as to leverage supporting empirical data with statistical modeling to improve the validity of neonatal mortality and cause-of-death estimates.