Through Clara and Jan, Fiep had met the poets Adriaan Roland Holst and Simon Carmiggelt, and it was through them that after the war she ended up in the circles of Vrij Nederland magazine and Het Parool newspaper, where she soon also had many commissions from the previously illegal publishing house De Bezige Bij to illustrate novels such as Veuve Vesuvius by F. Bordewijk, Jane Eyre by Charlotte Bronte and The Red Shoes by Hans Christian Andersen. She lived in a room on the De Lairessestraat and spent a great deal of time at her drawing board. Making a weekly illustration for Vrij Nederland was quite a job, especially if it was about a serious topic.

First children’s books
In 1945 Fiep illustrated Henriette van Eyk’s children’s book Sneeuw. 
Fiep’s line drawings in blue were subtly worked in between the text and in the margins. They are of graceful little figures. In 1947 Fiep illustrated Het verloren schaap by Han G. Hoekstra, a book of poems for children. Striking features of the illustrations in this book were again their elegant lines and their humorous tone, which matched the poems perfectly. Her collaboration with Han G. Hoekstra was a source of inspiration to her, and Fiep was to work with him frequently.