Background: Key elements of instructional quality include the teacher's ability to immediately react in domain-specific classroom situations. Such skills -- defined as action-related skills -- can only be validly assessed using authentic representations of real-life teaching practice. However, research has not yet explained how teachers apply domain-specific knowledge for teaching and to what extent action-related skills are transferable from one domain to another. Aims: Our study aims to examine (1) the relationship between action-related skills, content knowledge, and pedagogical content knowledge, and (2) the domain specificity of action-related skills of (prospective) teachers in the two domains of mathematics and economics. Sample(s): We examined German pre-service and in-service teachers of mathematics (N = 239) and economics (N = 321), including n = 96 (prospective) teachers who teach both subjects. Methods: Action-related skills in mathematics and economics were measured using video-based performance assessments. Content knowledge and pedagogical content knowledge were assessed using established paper-pencil tests. Correlation analyses, linear regressions, and a path model were applied. Results: In mathematics and economics, we find a similar pattern of moderate correlations between action-related skills, content knowledge, and pedagogical content knowledge. Moreover, a significant correlation between action-related skills in mathematics and economics can be explained almost entirely by underlying relations between content knowledge and pedagogical content knowledge in both domains. Conclusions: Our findings suggest that action-related skills empirically differ from domain-specific knowledge and should be considered as domain-specific constructs. This indicates that teacher education should not only focus on domain-specific teacher knowledge, but may also provide learning opportunities for action-related skills in each domain.