Henri Polak was educated at the private Jewish 'school of master Halberstadt'. He resided in London for a few years and then became a committee member of the Dutch Association of Diamond Workers in Amsterdam.
After an all-out strike of diamond workers, the General Dutch Union of Diamond Workers (Algemeene Nederlandse Diamantbewerkers Bond - ANDB) was set up on 18 November 1894 in Café Centraal. Henri Polak was one of the initiators and he became chairman of the union. He furthermore became chairman of the International Union of Diamond Workers. On his initiative, the Dutch League of Trade Unions (Nederlands Verbond van Vakverenigingen - NVV) was set up in 1905.
When the Social-Democratic Workers Party (SDAP) was launched in 1894, Polak also belonged to the founding members. He is described as one of the so-called Twelve Apostles who launched the party. Henri Polak was the first social-democrat to be elected to the town council of Amsterdam. He also sat in the First and in the Second Chamber.
Henri Polak stimulated the members of his ANDB to develop themselves in the domain of art, music and literature. He furthermore had a specific interest in the protection of nature and historic preservation. He was a trustee of the Palestine Building Fund 'Keren Hajesod'. In 1932, the omni potent was appointed doctor honoris causa in the Arts by the University of Amsterdam.
In the thirties, he warned in no uncertain terms about the rise of national socialism. On 18 July 1940, he was one of the first to be arrested by the German occupiers. After six months he was accommodated in a 'rest home' where the senior medical officer made life difficult for him. In July 1942, he was allowed to go home in a critically ill condition and he died there six months later.
M.H. Gans, Memorboek. Platenatlas van het leven der joden in Nederland van de middeleeuwen tot 1940 (6e bijgewerkte druk; Baarn 1988) 747-748;
S. Bloemgarten and J. van Velzen, Joods Amsterdam in een bewogen tijd 1980-1940. Een beeldverhaal (Zwolle 1997) 72, 77;
Jewish Historical Museum, Documents collection, inv.nr 6488
See also his biography in Biografisch Woordenboek van het Socialisme en de Arbeidersbeweging in Nederland [in Dutch] and S. Bloemgarten, Henri Polak : sociaal democraat, 1868-1943 (Den Haag 1993).