She is also a board member of the Foundation ceci n'est pas une crise, created in 2013 in Belgium to respond to the challenges of cultural and identity populism.

In 1990, Frassoni started working for the Greens/EFA Group in the European Parliament in charge of constitutional matters, rule of law, procedures and immunities.

In that capacity, she worked closely with Adelaide Aglietta, Alexander Langer and Paul Lannoye and was heavily involved in the implementation of the European Parliament's new legislative competences, subsequent to the institutional reforms culminating in the Treaties of Maastricht, Amsterdam and Nice.

She also became involved in several specific environmental issues with a clear European dimension in terms of EU law, such as protection of the Ebro River in Spain, high-speed infrastructures like the Lyon-Turin tunnel, waste in Naples, etc.

This campaign was an innovative pilot project involving national Green parties which aimed at bringing the discussion on who leads the EU closer to the citizens and at "Europeanising" the elections for the European Parliament in 2014.

In 2019 she delivered a special Course on “Lobbies and groups of interest in the EU” at the Sant’Anna School of Advanced Studies, Pisa, Italy.

In 2010, she contributed to the book "Europa 2.0 Prospettive ed evoluzioni del sogno europeo", edited by Nicola Vallinoto and Simone Vannuccini, with a chapter on conditions for the relaunch of Europe's constitutional process.

[16] In 2016, she contributed to the book "Accountability, Transparency and Democracy in the Functioning of Bretton Woods Institutions", edited by Prof. Elena Sciso, with the chapter "Two concrete experiences".

[18] In 2018, she contributed to the book "Europee: dieci donne che fanno l'Europa" published by Textus Edizioni, of which she directs the series "Le vie da percorrere".

[20] Monica is actively involved in projects and events and writes publications on possible reforms on the European Union, focusing on the quality of democracy and the Green transformation of the economy.

[25] In 2010, Frassoni was nominated by the Foreign Policy magazine as one of the Top 100 Global Thinkers list, along with Marina Silva, Cécile Duflot and Renate Künast, for "taking Green mainstream".