The Portrait of Maertgen van Bilderbeecq (1633) in the Städel Museum in Frankfurt am Main raises numerous questions. In 1986, the Rembrandt Research Project expressed doubts about Rembrandt’s authorship in the execution of the lace cap, which led to the exclusion of the portrait from the Rembrandt Corpus in 2015. Micro-XRF examination has now provided new insights into the painting’s creation, giving a more detailed picture of the artist’s painting technique. Analytical results are presented and evaluated here in relation to other early Rembrandt portraits, with specific attention paid to the depiction of lace. By aiming to deepen knowledge of the work’s genesis, this examination contributes to the ongoing discussion of the portrait. A pivotal question is to what extent particular working conditions – namely, time constraints, collaboration and efficiency in approach – were formative factors in Rembrandt’s early portrait production while he was working for Hendrick Uylenburgh in the first half of the1630s.