Almaguer served in the
Peace Corps as a volunteer in
Orange Walk Town,
Belize from 1967 to 1969, as Associate PC Belize Country Director from 1974 to 1976, and as PC Country Director in
Honduras from 1976 to 1979. From 1979 to 1983, Almaguer served as Deputy Mission Director for the
United States Agency for International Development (USAID) in
Panama. From 1983 to 1986, Almaguer worked for USAID in
Washington, D.C. as Director of the Office of South American and Mexican Affairs. From 1986 to 1990, he served as USAID Mission Director in
Ecuador. During the 1990-91 academic year, Almaguer participated in the U.S. State Department's
Senior Seminar Program overseen by the U.S.
Foreign Service Institute. From 1991 to 1993, Almaguer served as USAID's Regional Mission Director for Eastern Europe, based in Washington. From 1993 to 1996, he served as USAID Deputy Assistant Administrator for Human Resources and Director of Personnel in Washington. From 1996 to 1999, he served as USAID Mission Director in
Bolivia. In 1999, Almaguer was nominated by President Bill Clinton and confirmed by the U.S. Senate to serve as
United States Ambassador to Honduras, where he served from August 1999 to September 2002. Almaguer retired from the
United States Foreign Service with the personal rank of
Career Minister in November 2002. From 2003 to 2005, Almaguer served as a Senior Adviser to the
Pan American Development Foundation, was a United States Delegate to the 60th annual meeting of the
United Nations Commission on Human Rights, and worked as an international consultant on economic and social development reforms. Almaguer was appointed as Secretary for Administration and Finance at the
Organization of American States, the third-ranking position at the OAS, in February 2005, where he served for almost six years. He retired from the OAS position in December 2010. Since retiring from the OAS, Almaguer has served on a number of Boards: He has served since 2012 on the Board of Trustees of the Pan American Agricultural University (aka, Zamorano), serving students from throughout the Americas. He also has served on the Board of the USAID Alumni Association (2012-2016). In 2016, Almaguer was appointed by U.S. Secretary of State John Kerry to serve on the Foreign Service Grievance Board (FSGB), a position to which he was reappointed by Secretary of State
Mike Pompeo in 2018. In 2017, Almaguer was elected as a member of the American Academy of Diplomacy. ==Personal life==