Antonia Grumbach practiced law at Patterson Belknap Webb and Tyler, where she chaired the Exempt Organizations Group, assisting nonprofits with corporate, tax and general governance advice in many sectors, including education, social services, health, human rights, philanthropy, and advocacy. Much of her work was global, ranging from the Middle East through Europe and Latin America, and nationally throughout the United States. She managed the firm in the 1990s and is retired, serving as Of Counsel to the firm, and taking on pro bono projects. Antonia has served on numerous nonprofit boards, including acting as co-chair of Teachers College, Columbia University, and as chair of Wildlife Conservation Society, a global conservation organization.