India's sex ratio at birth (SRB) has become increasingly masculine, coinciding with a declining total fertility rate. Couples often resort to sex-selective abortion or even infanticide to ensure the birth of a son. We use household-level data from all four waves of India's National Family Health Survey (NFHS) to investigate the effect of India's demographic transition on the SRB. Mixed-effects logit regression analysis demonstrates that since the early 1990s, the probability of a third-order birth being male is decreasing in the number of sons previously born, while for second-order births, this effect does not become apparent until the 2000s. Accounting for geographic heterogeneity in the fertility transition, we find additional heterogeneity in son preference and sex selection at the village/neighborhood level. This heterogeneity has strengthened over time at both second- and third-order births and in more and less gender skewed regions of the country, suggesting potential convergence in sex ratios across India. By incorporating the most recent 2015–16 round of the NFHS, we demonstrate that previously documented trends in sex selection continue, and additionally that sex selection is increasingly occurring at lower parities as the desire for a smaller family combines with the traditional preference for sons.