Couples in Turkey exhibit son preference through son-biased differential stopping behavior that does not cause a sex ratio imbalance in the population. Demand for sons leads to lower (higher) ratios of boys to girls in large (small) families. Girls are born earlier than their male siblings. Son-biased fertility behavior is persistent in response to decline in fertility over time and across households with parents from different backgrounds. Parents use contraceptive methods to halt fertility following a male birth. The sibling sex composition is associated with gender disparities in health. Among children who were born in the third parity or later, female infant mortality is 1.5 percentage points lower if the previous sibling is male. The female survival advantage, however, disappears if the previous sibling is female. Having an older female sibling shifts the gender gap in infant mortality rate by 2 percentage points in favor of males.