Ien of the Hill Vrijzinning in her youth was active in the Christian Youth Central, where she worked in the youth groups of the Liberal part of the Dutch Reformed Church. Van den Heuvel was since 1946 a member of the labour party (PvdA). She was Director of the Vrouwenkontakt in the Labour Party, later known as the Red Women. In 1974 she became a member of the First Chamber, and in the same year she followed André van der Louw on as Party Chairman. In 1975 she headed a delegation to PvdA-a visit to the GDR. Jan Nagel defended delegation upon your return, the Berlin wall as historically accurate, which it on sharp criticism came to be of Joop den Uyl .  at the time of her Presidency deteriorated the hitherto close links between the Labour Party and the German sister party SPD, on the other hand by the sharp rejection of the labour party SPD-Chancellor Radikalenerlass Burns, on the other hand, in the eyes of the SPD by the uncritical attitude of the labour party in front of the GDR.  In 1979, she was succeeded as party President by Max van den Berg. From 1979 to 1989 she was a member of the European Parliament.
Except as a party politician was Ien van den Heuvel active for peace organisations. From 1987 to 1991, she was President of the Interdenominational Peace Council (IKV).In an interview immediately on taking office as President in 1986 in the core sheet with Pam t, they noted to her disappointment that her religious background, the cultural liberalism, as movement within the churches to the decline was. They further said "a radical pacifist of the small steps", which like to involve religious and non-religious pacifists within the broad peace movement, but that they not only wanted to testify but also "wanted to see a little result". About threads in the peace movement in the years before that had raged about civil disobedience, said Van den Heuvel that disapproving of civil disobedience for her "no dogma" was. "But if you want to play in the total power struggle that politics of course, do you also as social movement be wise to, to view the rules of the parliamentary democracy as pure as possible to handle. Ien Van den Heuvel said in the interview that took place just after the meeting between Reagan and Gorbachev in Reykjavik -get annoyed at people who any optimism about developments in Eastern Europe the ground inboren and thus have an excuse to think having to do nothing with it. "By some people to the ground every optimistic sound you hear in stamping, otherwise you're not a good Democrat or so." But they did not take that you're in the other extreme is to expire, "as people who in their greed for relaxation in these countries forget that there are still things happening that really don't stand up to scrutiny, especially if you look to the human rights ." Ien van den Heuvel, as Chairman of the IKV warmly supported the policy of this organization, that was a combination of resistance against nuclear weapons and support for the democratic opposition in the Communist countries.