Scientific Study from the year 2024 in the subject Pedagogy - The Teacher, Educational Leadership, , language: English, abstract: This study investigates the landscape of online teacher professional development (PD) through a comprehensive analysis of two large-scale datasets. The data for this paper has been collected from two international assessments, namely the Teaching and Learning International Survey (TALIS) 2018 and the National Teacher and Principal Survey (NTPS) 2017-18. Gender, Teaching Experience, Subjects Taught, School Locations, Internet Connection and the Availability of Professional Development Teachers' beliefs about the value of participating in professional development also have Variables that affect Online PD Participation Patterns, Teaching Practices, and Effectiveness. Descriptive findings document effects at teacher, school, and country levels and shed light on online PD programs' elaborate and hierarchical structure. According to the aforementioned results, a high percentage of PD¿s online participation is affirmed (68.7% TALIS, 72.3% NTPS) as well the positive outcomes of the analyzed PD on teaching practices, especially regarding ICT use (Cohen¿s d = 0.59). ICT self-efficacy was also the most significant predictor of perceived online PD effectiveness (¿ = 0. 227, p < .001). The study has also established institutional and design variables, augmenting the results of online PD. Thus, these results enhance the theoretical knowledge of online teacher learning and provide suggestions for practical applications in learning and designing efficient online PD models. The study lays the foundation for further research on the current state of teachers¿ professional learning in the context of digital transformation.