Teachers’ subject-specific cognition is seen as an important factor for the quality of instruction and, accordingly, student learning. However, in-depth research on these relations can only be carried out if a sound theoretical model for subject-specific teacher cognition (knowledge and competence/practical skills) and—in the case of a quantitative research approach—corresponding measures are available. The subject-specific cognition can be modeled as basic professional knowledge (BK) complemented by two further components of reflective competence (RC) and action-related competence (AC) with a close connection to professional demands. In order to implement these subject-specific demands rigorously, we developed innovative standardized measures for primary mathematics teachers. In particular, we argue that video-based items that are implemented in a speed condition and rated as holistic observations are well suited to realize the assessment of action-related competence. This article gives a detailed insight into the test development as well as the coding and scoring procedure and focuses on validation efforts. The study is based on the data of 85 in-service primary mathematics teachers and shows the viability of the approach. Classical scale analyses as well as confirmatory factor analyses and the comparison of different models as well as teacher groups (mathematics certified vs. non-mathematics certified teachers) give evidence for the validity and reliability of the measures.