Addressing socioscientific issues (SSIs) in the classroom provides an appropriate context to concentrate on several components of scientific literacy. The purpose of the study was to develop a valid, reliable, instrument to assess teachers' PCK for biological socioscientific issues (PCK-BSSIs). In this paper, two aspects of the research have been described; the framework on which PCK-BSSI is based, and the development, administration, and analysis procedures of the instrument. The PCK-BSSIs will allow re-searchers to explore teachers' understanding of SSIs, how teachers' PCK for BSSIs develops over time, and the relative efficacy of various professional developments. (C) 2020 Elsevier Ltd. All rights reserved.