Hannah Clarke was born in Boston on February 27, 1734, the second recorded child and eldest daughter of Richard Clarke and Elizabeth Winslow Clarke. Her father, a Harvard graduate, was developing the Atlantic trading business that would make the Clarkes one of Boston’s most prosperous merchant families. Her mother came from the well-connected Winslow family, joining Hannah by ancestry and kinship to several generations of prominent New England families. Hannah grew up with eleven brothers and sisters in a household whose fortunes were tied to imported goods, overseas correspondence, shipping, and credit. Among her siblings were William, Edward, Joseph Lee, Mary, Jonathan, Susanna, Isaac Winslow, Sarah, Lucy, and a younger Richard. Several of them would later enter the family’s commercial or social network.

The surviving family and business summaries reveal much more about the Clarkes’ trade than about Hannah’s individual childhood or schooling. As the daughter of an affluent Boston merchant, she likely received the domestic, religious, and social instruction considered suitable for a girl expected to manage a substantial household, but the precise form of her education is not documented in the available records. She came of age while Boston expanded as a center of imperial commerce and while her father traded with London, Canada, the West Indies, and neighboring ports. Tea, sugar, molasses, oil, and potash all appeared in the family’s accounts.

Hannah was twenty-seven when Henry Bromfield’s first wife, Margaret Fayerweather Bromfield, died in 1761. On September 23, 1762, Hannah married Bromfield, a prosperous merchant and widower with children. The marriage placed her at the center of another important mercantile household and made her stepmother to his existing family. Their daughter Elizabeth Bromfield was born in August 1763.