Recent literature on pre-service teacher education emphasizes the importance of student teaching in teacher education programs. For this reason, this study was designed to determine the self-reported problems of pre-service teachers' teaching and to find out whether there is any kind of change in the problems of student teachers throughout the practicum. Ninety-nine Turkish EFL teachers were chosen as the participants of the study who were told to write reflections on their each teaching experience. Data were analyzed by dividing the reflection reports into communication units. Each communication unit was named and labeled according to problems in student teachers' teaching experiences. Categories were also divided into three time periods considering the time of the communication units as stated by student teachers. The analysis of the data revealed five main categories as the sources of student teachers' problems. The analysis suggested that most of the problems of student teachers decrease in frequency whereas some of them increase towards the end of the practicum, or do not show any changes throughout the practicum. Consequently, the study stresses the need for modification in the teacher training curriculum and offers behavioral guidelines to student teachers, cooperating teachers, and university supervisors.