Problem Statement: One way to delineate the main characteristics of effective teaching within the higher education system is to gather college students' opinions of an effective instructor. Research based on students' perceptions of efficient teaching revealed a series of teaching behaviors setting the distinction between good and poor teaching. However, studies also indicate differences across culture, and in Turkey, there has been little research on the topic. Purpose of Study: The goal of this study was to determine instructor and course characteristics and teaching dimensions that discriminate between instructors who received the highest and the lowest student ratings within a Turkish college setting, by incorporating both quantitative and qualitative methods. Method: A total of 23,814 students across different departments in the university rated 630 instructors on a scale developed to assess students' perceptions of instructors' performance. In addition, students were asked to respond to an open-ended question to provide their own impressions of each instructor. Then, students' ratings were analyzed by means of discriminative functional analysis, and written statements provided by students were analyzed via content-analysis techniques by using a combination of manual and computer-assisted methods (NVivo 9). Findings and Results: According to the quantitative analyses, although course and instructor characteristics were weak in discriminating the groups, all teaching dimensions (relationships with students, effective teaching, exams and evaluation, contribution to generic skills, class interaction, and organization and planning) were very useful in discriminating the instructors who received the best and the poorest ratings. Also, qualitative analysis revealed 4 themes consistently distinguishing the two groups: lecturing, relationship with the students, knowledge and expertise, and exams and evaluation. Conclusions and Recommendations: This study replicates the existing literature on student perceptions of effective teaching, with a culturally different, large sample. It also adds support to the notion that there are teaching behaviors, such as lecturing skills, fair evaluations, respect and interest toward students, and demonstrating expertise, that help draw the distinction between good and poor teaching in the eyes of students and that could therefore assist the improvements efforts of teacher education.