One of thirteen children, Robert Mara Adger was born in Charleston, South Carolina. His father, Robert Adger, was black, and his mother, Mary Ann Morong, was Native American. In 1848 the family moved to Philadelphia, Pennsylvania. Adger's father first found a job as a waiter in the Old Merchant's Hotel. Later, while working as a nurse, he industriously saved enough funds to open a furniture business. He was involved in many activities and was a founder of the Benjamin Banneker Institute.
Robert Mara Adger received his early training at the Bird School, an early black educational institution in the United States. During his teenage years, he worked in his father's furniture stores, which had expanded from one in 1850 to three by 1858 Serving as a manager provided him with the business experience that he later found valuable as director of the Philadelphia Building and ...