In the study described in this article, primary school teachers' pedagogical content knowledge (PCK) of technology education was measured with a multiple choice test; the Teaching of Technology Test (TTT). The aim of the study was to explore the latent factor structure of PCK, which is considered to be a crucial and distinctive domain of teacher knowledge. As far as known, it is the first time that PCK is approached in this way. Many different components of PCK have been proposed in an attempt to define the concept, but these components have never been statistically confirmed. Three components were selected as the main knowledge components of PCK for technology education in primary schools: (1) Knowledge of pupils' concept of technology and knowledge of their pre and misconceptions related to technology; (2) Knowledge of the nature and purpose of technology education; (3) Knowledge of pedagogical approaches and teaching strategies for technology education. The results of this study gave useful insights into primary school teachers' PCK of technology education. It appeared that the theoretically predefined knowledge components could be indentified as latent factors. Furthermore, PCK could be characterized as a heterogeneous construct. That is, it consists of many intrinsic elements, which are difficult to unravel. Although measurement of PCK with a multiple-choice test has clear-cut advantages compared to qualitative methods and the results of the TTT are promising, further steps should be taken to reach satisfactory psychometric properties for practical application. This article provides ideas on how to (further) develop a multiple choice test to measure PCK. (Contains 4 tables and 4 figures.)