As an Open Society Fellow, Vandenberg established The Human Trafficking Pro Bono Legal Center, a clearing house that brings attorneys together with human trafficking survivors seeking legal assistance. The organization works to increase the range of legal options offered to trafficking victims in the United States. By advocating with non-governmental organization leaders, training lawyers, and mentoring attorneys handling pro bono trafficking cases. She received the Truman Foundation's 2013 Stevens Award.
Previously, Vandenberg was a partner in the Litigation Department of the law firm Jenner and Block LLP, where she focused on complex commercial litigation and Foreign Corrupt Practices Act matters. She served as a senior member of the firm’s Pro Bono Committee. As the Europe Researcher for Human Rights Watch’s Women’s Rights Division (1998–2002), she participated in the negotiations for the United Nations Trafficking Protocol in Vienna, Austria. A Rhodes Scholar and Truman Scholar, Vandenberg has also taught as adjunct faculty at the American University Washington College of Law.