["Studies in Family Planning, EarlyView. ", "\nAbstract\nEducational expansion is widely regarded as a central mechanism in fertility transitions, yet some research suggests its role may be more modest. This study analyzes birth histories from 414 surveys in 72 low‐ and middle‐income countries to reassess the contribution of the shift in the educational composition of the population to fertility declines. We reconstruct fertility trends by educational level over several decades and apply the Kitagawa decomposition method to determine whether declines primarily reflect shifts in educational composition or changes in fertility within educational groups. On average, educational expansion accounts for approximately 30 percent of the decline in fertility, with substantial variation across regions, countries, and over time. The declines primarily reflect fertility changes within educational groups, especially among women without secondary education, rather than shifts in the educational composition of the population. However, although educational progress is neither necessary nor sufficient for fertility decline, it has consistently contributed to fertility reductions and is likely to remain an important component of fertility transitions.\n"]