[1] Etty Hillesum began writing her diary in March 1941, possibly at the suggestion of her analyst Julius Spier,[3]: 89  whom she had been consulting for a month.

[2]: 29–34 Her diaries record the increasing anti-Jewish measures imposed by the occupying German army, and the growing uncertainty about the fate of fellow Jews who had been deported by them.

[5] This refusal was due to her belief that her duty was to support others scheduled to be transported from Westerbork to the concentration camps in German-occupied Poland and Germany.

Mischa Hillesum remained in Auschwitz until October 1943, when he was moved to the Warsaw Ghetto, where, according to the Red Cross, he died before 31 March 1944.

[3]: 75 Etty Hillesum's youth was chaotic and turbulent, possibly resulting from her emotionally unstable family, to which she herself referred as a "madhouse".

[7]: 215  Hillesum addressed God repeatedly in her diaries, regarding him not as a saviour, but as a power one must nurture inside of oneself: "Alas, there doesn't seem to be much You Yourself can do about our circumstances, about our lives.

She writes during her time at Westerbork: "The sky is full of birds, the purple lupins stand up so regally and peacefully, two little old women have sat down for a chat, the sun is shining on my face – and right before our eyes, mass murder...

"[7]: 360 Before she left for Westerbork, Etty Hillesum gave her diaries to Maria Tuinzing, with the instruction they be passed to Klaas Smelik for publication, should she not survive.

An abridged edition of her diaries appeared in 1981 under the title Het verstoorde leven ('An Interrupted Life'), followed by a collection of her letters from Westerbork.

[3]: 74 [7]: 360 David Brooks sees Hillesum's ability to hold both intellectual skepticism yet humanitarian vulnerability in How to Stay Sane in Brutalizing Times.

[12] Rowan Rheingans has drawn on Hillesum's writing, particularly on the coexistence of beauty and horror, and on allowing room for sorrow, in her album "The lines we draw together".

On 13 June 2006, the Etty Hillesum Research Centre (EHOC) was officially opened as part of Ghent University with a celebration at Sint-Pietersplein 5.

There is also a modest museum dedicated to her memory, the Etty Hillesum Centre, housed at Roggestraat 3, Deventer, the location of a former synagogue and Jewish school.