She gradually rose from the ranks and was transferred from one agency to another until her appointment as Chief of the Manpower Development and Utilization Division in the Department of Labor and Employment (DOLE) until 1977.
[1] In 2001, she led an Executive Search Committee tasked to find qualified professionals to man key positions in the Cabinet and attached agencies of President Gloria Macapagal Arroyo.
[1] In 2006, Santo Tomas was appointed by President Arroyo as chair of the board of directors of the Development Bank of the Philippines, a state-owned financial institution with a nationwide branch office network.
She was a Ten Outstanding Women in the Nation's Service Awardee for Public Administration; an Outstanding Graduate of the Career Executive Service Development Program Phase 2; an Edward S. Mason Fellow at John F. Kennedy School of Government; a Harvard University Fellow; a Grantee of the United States International Visitor Program, and the United States International Communication Agency.
[1] Santo Tomas is a Professorial Lecturer at the University of the Philippines Los Baños and a Consultant at the Communication Technology for Rural Education.