Based on the prerequisite role of teachers' professional development for students' progress, our study aimed to shift the DeSeCo (Definition and Selection of Competencies; OECD, 2002) theoretical model from students' competencies for life challenges to teachers' professional context by creating a reliable, valid questionnaire based on the three DeSeCo's theoretical factors: using tools interactively; functioning in socially heterogeneous groups; and acting autonomously. Results demonstrated validity for the 35-item Life Challenges Teacher Inventory, which was tested on 412 teachers from different school types and disciplines. Theoretical and practical implications are discussed for professional education and growth. (Contains 5 figures and 3 tables.)