William Kirby, Esq.

Meet William Kirby, Philadelphia Family Law Attorney

William Kirby is a Philadelphia-based family law attorney who helps people successfully resolve legal matters including divorce, separation, child custody, support disputes, property division, and the resulting tax consequences of those matters. As their advocate, he helps his clients make informed decisions for their best possible future.

The foundation of William’s successful family law practice is his strong skillset in both litigation and negotiation. He refined those skills as an attorney in the U. S. Marine Corps and then as a business litigator representing Fortune 500 companies.  During these formative years, Bill learned the motto of “sensible always and hard-nosed when needed.”  Now, as a family law attorney, he employs these lessons and skills to improve the lives of his clients. He is passionate about helping people regain control of their lives and protecting their rights.

Having been a single father, Bill’s personal experience with child custody proceedings and mediation allows him to better appreciate the compassion needed to navigate such matters and achieve positive solutions that enable his clients and their families to move forward with their new beginnings.

While earning his Bachelor of Science in Economics from the United States Naval Academy, William was named an Arleigh Burke Academic Scholar. As a U. S. Marine Corps First Lieutenant, he was awarded the Marine Corps Funded Law Education Program scholarship. Bill attended Duke University School of Law, where he received his law degree in 2004. He is a retired Major in the U.S. Marine Corps.

Although he was born in Scotland, William was raised in Burlington County, New Jersey. He joined Petrelli Previtera Schimmel in 2019 and practices in the firm’s Philadelphia office. Bill is a member of the Pennsylvania and American Bar Association Family Law Sections. He is licensed to practice in Pennsylvania, U.S. District Court Eastern District of Pennsylvania, Maryland, and the District of Columbia.

When not practicing law, William enjoys teaching group exercise classes, cooking and spending time with his daughter, Makenzie, whom he affectionately calls “Mak Attack.”


  • Juris Doctor, Duke University School of Law, 2004
  • Bachelor of Science, United States Naval Academy, 1998

Professional Associations

    • American Bar Association, Family Law Section
    • Pennsylvania Bar Association, Family Law Section
    • Maryland Bar Association
    • U.S. Court of Appeals for the Armed Forces
    • U.S. Navy-Marine Corps Court of Criminal Appeals

Jurisdictions Admitted to Practice

  • Pennsylvania
  • New Jersey
  • Maryland
  • District of Columbia
  • U.S. District Court Eastern District of Pennsylvania

What Clients Say About Us

This firm is very good. They gave me good advice and so far I’ll still have custody of my grandchildren and with his help I shall maintain that custody. Superior.- A Family Law Client, Philadelphia, PA
Petrelli Previtera Schimmel worked with me on case and he was great. His staff and lawyers are so friendly and helpful. You can tell they cared by how quickly they returned my calls. Even if Mr. Petrelli was unavailable to assist me, his associate was there to answer my questions. I am very happy with their work and their rates are reasonable. If you need a family lawyer, these are the guys to go to.- A Pennsylvania Client, Delaware County, PA