Measuring the quality of teacher professional development: A large-scale validation study of an 18-item instrument for daily use

This study introduces the Teacher Professional Development (TPD) Monitor, an 18-item instrument designed to assess the quality of formal learning opportunities (e.g. courses, workshops), for in-service teachers across all grade levels of general education. By evaluating these opportunities across four critical dimensions—clarity and structure, cognitive activation, collaboration, practical relevance—the TPD Monitor provides a comprehensive framework for assessing the effectiveness of professional development programs. Developed and validated with data from 2314 in-service teachers actively teaching in primary, secondary, special education, and vocational schools, each participating in one of 173 distinct TPD courses, this instrument is supported by multi-level confirmatory factor analysis that confirmed its structure, offering robust evidence of its validity and reliability. Furthermore, measurement invariance was achieved, allowing for meaningful comparisons between subgroups. The TPD Monitor is a valuable and practical tool enabling TPD providers to design effective courses and allowing to monitor and improve the quality of TPD programs.