<p>Spanish rural society has undergone profound transformations over time, historically characterized by its traditional structure and a marked preference for male children. Extensive research has shown that this preference led to higher mortality rates among girls, reflecting the disadvantages they faced from birth. However, the twentieth century saw a gradual shift toward a more balanced preference for having both boys and girls. Drawing on a comprehensive database of the life trajectories of 2,732 complete families who had children between 1880 and 1985, this article is groundbreaking in its long-term exploration of the evolution of gender preferences in offspring in rural Spain, focusing on fertility decisions and parental investment based on the child’s gender. Our analysis confirms that the shift toward favoring a balanced boy–girl combination began in the early decades of the twentieth century. Nonetheless, the equalization of investments in children’s well-being, including both health and education, progressed more slowly. Notably, significant improvements in human capital investment were only achieved by women born in the late twentieth century, who now form part of the current workforce.</p>