From 1987 onwards, it entered all the legislative, and municipal elections as part of Unitary Democratic Coalition, which also includes the PCP.

In the end of the 1970s, Earth was facing new ecological problems, such as the greenhouse effect and the depletion of the ozone layer and the lack of awareness of this in Portuguese society, along with the lack of an organized Ecologist movement, led to the foundation of the Ecologist Party "The Greens" in order to put such problems on the political agenda.

The growth of the Party throughout the country allowed many members to integrate the electoral lists of the CDU, some being elected to very different tasks.

[9] The PEV edits a newspaper, the Folha Verde (Green Leaf), which received several press prizes for its unique design and style.

[6] In elections, the PEV is closely allied with the Portuguese Communist Party, first in the Unitary Democratic Coalition.