荷蘭國會
In 1966 Van Mierlo together with Hans Gruijters founded the Democrats 66 party after continuing frustrations with "The Establishment" parties. Van Mierlo was selected as Leader and Chairman of the Democrats 66 on 14 October 1966. For the Dutch general election of 1967 Van Mierlo was the "lijsttrekker" (top candidate) and won seven seats in the House of Representatives, the first time the Democrats 66 won representation in the States General of the Netherlands.