Sixteenth-century Spain was at the vanguard of European collegiate bureaucratic rule and imperial governance. This article argues that its Council of the Indies became substantially more bureaucratic partly due to the influence of women. Vassals’ attempts to shape ministers’ decisions via female connections prompted the council's fundamental 1542 and 1571 guidelines. Subsequently, Madrid's anxieties about women's sway, and surfeits of Indies commodities, stirred misogynistic treatises, royal scrutiny, and an increasingly explicit masculine ministerial ethos. Women's influence over council operations nonetheless persisted, through near-invisible labor contributions and petitions. One female author in Peru even envisioned influential women directing the empire.