This qualitative exploratory study examines the nature of teacher leadership in Jyväskylä Finland by examining the principals' and teachers' perceptions of the phenomenon. There is a substantial international literature focusing on teacher leadership that has contributed to the grounding of this study (Harris 2003a). Although a significant part of the literature on teacher leadership is generated by scholars in the United States of America Canada and the United Kingdom few studies have been published that focus on the Finnish school context. This study makes a contribution towards building a knowledge base on teacher leadership in Finland. The data was gathered by semi-structured interviews conducted in four different upper secondary schools. Eight teachers were interviewed in focus groups; individual interviews were carried out with four teachers and four principals. The data was analyzed using the content analysis method. The findings from the four schools indicate collaborative teamwork fluid and emergent leadership that embedded teacher leadership characteristics perceived from both principals' and teachers' perspectives.