While new empirical findings and theoretical frameworks provide insight into the interrelations between socioeconomic development, gender equity, and low fertility, puzzling exceptions and outliers in these findings call for a more all-encompassing framework to understand the inter-play between these processes. We argue that the pace and onset of development are two important factors to be considered when analyzing gender equity and fertility. Within the developed world, “first-wave developers”—or countries that began socioeconomic development in the 19th/early 20th century – currently have much higher fertility levels than “late developers”. We lay out a novel theoretical approach to explain why this is the case and provide empirical evidence to support our argument. Our approach not only explains historical periods of low fertility but also sheds light on why there exists such large variance in fertility rates among to-day’s developed countries.