The objective of this study is to examine the relationships between the levels of schools for being professional learning communities and teacher professionalism based on teachers' perceptions. The participants were a total of 543 teachers working at elementary, middle and high schools in the Eyüp District of Istanbul. The data were gathered through the "Professional Learning Community Scale" and the "Teacher Professionalism Scale". The results showed that the teachers' perceptions on schools becoming professional learning communities and teacher professionalism were above moderate level. There were positive and significant correlations between all dimensions regarding the levels of schools for being professional learning communities, and teacher professionalism. Besides, the only significant and positive predictor of teacher professionalism was found to be the dimension "collective learning and applications" of professional learning community scale.