Adaptive calibration models suggest that features of people's childhood ecologies can shape their reproductive outcomes in adulthood. Given the importance of dyadic sexual desire (i.e., desire for sex with a partner) for relationships and reproduction, we examined the extent to which people's childhood ecologies-especially the unpredictability of those ecologies-adaptively calibrate such desire. Nevertheless, because female (versus male) sexual desire is presumed to be more sensitive to situational factors, and because hormonal contraceptives alter myriad aspects of female physiology that influence female sexual desire, we predicted that adaptive calibration of dyadic sexual desire would emerge more strongly for naturally cycling females (versus females who use hormonal contraceptives and versus males). In Study 1, a total of 630 participants (159 males, 203 naturally cycling females, and 268 females using hormonal contraceptives) completed questionnaires assessing the harshness and unpredictability of their childhood ecologies as well as their sexual desire. Consistent with predictions, childhood unpredictability (but not harshness) was positively associated with dyadic (but not solitary) sexual desire among naturally cycling females (but not among females using hormonal contraceptives nor among males). Study 2, which consisted of 736 females (307 naturally cycling females, 429 females using hormonal contraceptives), replicated this pattern of results for females. These findings add to a growing literature suggesting that the instability of people's early childhood ecologies can adaptively calibrate their adult reproductive motivations and behaviors, including their dyadic sexual desire. Not only is the current finding among the first to show that some adaptive calibration processes may be sex differentiated, it further highlights that hormonal contraceptives, which alter the evolved reproductive physiology of females, may disrupt adaptive calibration processes (though such disruption may not be inherently negative).