This paper reports findings from nine case studies of headteachers in challenging urban contexts in Poland and England. These headteachers are perceived to be successful in their roles, making a significant difference to the quality of education in their schools. The paper focuses on formative experiences from these headteachers’ stories. The main research question addressed by this paper is: What can we learn from successful leaders’ professional development by reconstructing their career stories? The comparative analysis of the stories revealed some important recurring common themes and identified some leadership formative experiences in the paths of these headteachers’ professional lives. Findings showed that headteachers during their first years of their headship were especially vulnerable. Some incidents and experiences proved decisive in determining their further career trajectories.