As Benjamin rose from printer to postmaster, William rose along with him. Will served ably as the Philadelphia Postmaster, and later as the Comptroller of the entire North American Postal system at age 23. As Clerk for the Pennsylvania Assembly, William saw the intricate workings of the legal system and decided to pursue law as a career. He served an internship with Joseph Galloway in Philadelphia.

In spite of his various positions and duties, William was quite active in Philadelphia society. He was a member of the Masons, The American Philosophical Society, and the New Junto (the latter was modelled after his father's famed discussion club). He was also one of the organizers of the Philadelphia Dancing Assemblies. W.S. Randall, in his book on the Franklin's, A Little Revenge, believes that it was at one of these assemblies that William, at age 24, met and courted the 17 year old debutante, Elizabeth Graeme.

Elizabeth's father, Dr. Thomas Graeme, had worked with the elder Franklin to form the first fire insurance company in the colonies, The Philadelphia Contributorship. (Ironically, that was the same company that Mr. Welsh Strawbridge used to insure Graeme Park in 1920. That was the source of the plaque on the back wall of the Keith Mansion). But later disagreements over the proprietary government of the Penns led to often bitter animosity between the two patriarchs. Neither father thought that this love match was a good one.

William courted Elizabeth with visits to Graeme Park. In the summer of 1756, William proposed to "Betsy". She accepted with provision that William never engage in factional politics, and that he stop writing satires on the Proprietary Party since many of the members were friends of Dr. Graeme.

Ben Franklin was appointed Agent of the Pennsylvania Assembly and he was sent to petition the Parliament and the Crown for a royal, rather than a proprietary, government for Pennsylvania.

Ben offered to pay for William's legal education if Will travelled with him to London. Ben also made William his heir and executor when William accepted. Before he left for England, he proposed a secret wedding to Elizabeth, but she was afraid to further anger her father. William decided to await his return to Philadelphia as a lawyer, and a gentleman with high prospects.

While in England, Ben urged his son to write "An Historical Review of the Constitution and Government of Pennsylvania", a thinly disguised attack on the Penn Proprietary. This effectively broke his promise to avoid partisan politics that would anger Dr. Graeme. Elizabeth wrote a scathing letter chastising William for that change, and for not writing her frequently.

His reply professed faithfulness, but his attraction was fading with the distance and time. It had been over a year and a half since he had left Philadelphia. His last written words to her were to "forget the man who in all probability could never have it in his power to be so happy as to contribute to your happiness. I, only I, have to learn forgetfulness." (October 24, 1758) This was his last letter to Elizabeth. He considered the engagement broken, but Elizabeth did not. When William returned to America in 1761, it was as Governor of New Jersey, and married. Elizabeth became so despondent that for a while she became a recluse, spending months painstakingly translating Fenelon's "Telemachus" from French to English. Later her parents sent her to England so as to avoid and to forget him.

While William was still in London he continued as his father's assistant and continued his law studies. He met, courted, and married Elizabeth Downes, a daughter of a wealthy Barbados sugar planter.

William's service as the last of the Royal Governors of New Jersey, and his position during the American Revolutionary War are worthy of discussion at another time. His sense of honor, law, and duty to his family, father, and country, as he saw it, deserve great respect.