What is the nature of teachers' pedagogical knowledge? The Innovative Teaching for Effective Learning Teacher Knowledge Survey (ITEL TKS) set out to answer this question in a pilot study that ran in five countries: Estonia, Greece, Hungary Israel, and the Slovak Republic. Using convenience samples, the pilot assessed the pedagogical knowledge base of teachers, teacher candidates and teacher educators. Pedagogical knowledge was broken down into the domains of assessment, instructional processes and learning processes. The link between teachers' knowledge and characteristics of teacher education systems, opportunities to learn and motivational characteristics was also examined. The ITEL TKS pilot demonstrated the feasibility of researching teachers' pedagogical knowledge profiles across countries, and validated an innovative instrument for assessing general pedagogical knowledge in an internationally comparative way. It also allowed for reflection on potential adaptations to strengthen the design of future work. The results serve as a template for a larger-scale study to explore teacher knowledge and competences in nationally representative samples.