While earning her advanced degree she worked at the U.S. Embassy in Caracas, implementing the Alliance for Progress (ALPRO) programme established by President John F. Kennedy, which assisted the creation of libraries and the distribution of books within South America.

They returned to Spain in 1972, to live in Pamplona in the Navarre autonomous community, where their fourth son, Enekoitz, was born.

The library began operating in January 1982 as a centre for bibliographic documentation and archives on issues discussed in Parliament.

After obtaining the Urquijo collection, Ametzaga directed the publication of six bibliographic catalogues of the library, a milestone in the history of bibliography in the Basque Country.

[4][5] In the first years of the transition in Spain after the death of the dictator, Francisco Franco, Ametzaga was very active in politics.

From 2007 to 2011 she was a councillor in the Valle de Egüés, representing the Nafarroa Bai group, a coalition of Basque nationalists and left-wing parties, and from 2015 to 2019 she was a member of the Alzuza Council.