The aim of this study was to compare the number of Professional Development (PD) activities the teachers attended, compare them by demographic variables, and investigate the relationship between these activities and teacher leadership and life satisfaction. The study sample was determined by the simple random sampling method and consisted of 821 teachers working in various provinces in Turkey. The results of the study are summarized as follows: A significant weak positive correlation was found between the teachers' beliefs regarding the function and importance of PD activities and the total number of PD activities they attended in 2020. It was found that the teachers' monthly income and the PD activities they attended per week and per year had a significant positive effect on their leadership behavior and that the leadership behaviors of teachers had a significant positive effect on their life satisfaction.