Rebecca Lukens was born on January 6, 1794, to Isaac Pennock and Martha Webb Pennock. Rebecca’s mother, Martha, was from an established and wealthy Quaker family, farmers who were some of the early settlers of Chester County. Eighteenth and nineteenth-century Quaker beliefs included strong communal ties, anti-war and anti-slavery sentiments, keen business principles, and the support of education and leadership roles for women. Rebecca was strongly influenced by these beliefs.

As the oldest child, Rebecca fell into the traditional role of an eldest son — at the father’s side learning the family business. Isaac and Martha would not have a son until their fourth child and Isaac sometimes took young Rebecca into the mill and on trips to visit his suppliers at the forges. Rebecca was a keen observer and her father was willing to explain the workings of the mill and a business.

Quakers believed greatly in equality, including allowing both boys and girls the same educational opportunities. Isaac and Martha Pennock shared this same belief, and in September 1806, they sent Rebecca to Westtown School, a nearby Quaker boarding school. The curriculum included math, accounting, penmanship, and other practical subjects. Rebecca then continued her education at the Wilmington Boarding School for Girls. While home from school, Rebecca joined her father at the iron works, continuing her education in business and industry. These educational years provided Rebecca with the foundation needed to became an ironmaster and America's first female industrialist.