Timo Leuders is professor of mathematics education and vice president for research at the University of Education Freiburg, Germany. His research interests comprise the psychology of teaching and learning of mathematics at secondary level and pre-service and in-service teacher education.Juliane Leuders is a lecturer at the Institute of Mathematics education at the University of Education Freiburg, Germany. She earned a doctoral degree at the Faculty of Rehabilitation sciences at TU Dortmund University. In research and teaching, she focusses on inclusive education, mathematics education, and early childhood education. Kathleen Philipp is professor for teaching and learning of mathematics at the University of Applied Sciences and Arts of Northwestern Switzerland, School of Education. The focus of her research is on mathematical thinking of students and on competences of mathematics teachers at primary level.

• Part 1. The Nature of Diagnostic Competence – Conceptualizing and Measuring Facets of Diagnostic Competence.- 1. Diagnostic Competence of Mathematics Teachers – Unpacking a Complex Construct.- 2. Diagnostic Skills of Mathematics Teachers in the COACTIV Study.- 3. Competences of Mathematics Teachers in Diagnosing Teaching Situations and Offering Feedback to Students: Specificity, consistency and reification of Pedagogical and Mathematical Discourses.- 4. Diagnostic Competence for Dealing with Students’ errors – Fostering Diagnostic Competence in Error Situations.- 5. Factors Influencing the Accuracy of Diagnostic Judgments.- 6. Diagnostic Competences of Mathematics Teachers with a View to Processes and Knowledge Resources.- 7. Revealing and Promoting Pre-Service Teachers’ Diagnostic Strategies in Mathematical Interviews with First-Graders.-  Part 2. Developing Diagnostic Competence and Applying Diagnostic Competence in the Classroom – Models for Teacher Training.- 8. Developing Diagnostic Competence Through Professional Learning Communities.- 9. Supporting Mathematics Teacher Diagnostic Competence Through the use of one-to-one, Taskbased Assessment Interviews.- 10. Diagnosing Learning Goals: An Often Overlooked Teaching Competency.- 11. Improving Teachers’ Assessment Literacy in Singapore Mathematics Classrooms: Authentic Assessment Task Design.- 12. Developing Prospective Teachers’ Ability to Diagnose Evidence of Student Thinking: Replicating a Classroom Intervention.- 13. Specific Mathematics Assessments that Reveal Thinking: An Online Tool to Build Teachers’ Diagnostic Competence and Support Teaching.