This study examined the meaning of effective teaching and instructional flexibility at the post secondary level to see where instructional flexibility fits into the frame of effective teaching. Five hundred college students and fifteen instructors participated in this study. Student participants shared their perceptions of instructional flexibility and effective teaching through open-ended questions using an online survey. Instructor participants shared their concepts of both constructs through one-on-one interviews. Given that the focus of this study was on the perceptions of college instructors and students of what effective teaching and flexibility in teaching encompass, all collected data were analyzed using a grounded theory approach (Strauss & Corbin, 1998). The emergent model of effective teaching and instructional flexibility comprised four themes: (a) teaching for the progress of learning; (b) a teacher’s role as the “human” persona; (c) teaching to bridge the gap from facts to understanding; (d) a teacher’s role as content expert. These four themes could be seen as representing the concept of instructional flexibility (Themes 1 and 2), and the concept of effective teaching (Themes 3 and 4) at the postsecondary level. Results indicated that a flexible teacher was portrayed as someone who was responsive and attentive to the needs of individual students whereas an effective teacher was described as someone who was successful in helping students understand important course concepts. Further, results showed that instructional flexibility was considered to be an important component of effective teaching both by college students and instructors. Regarding the association between teaching effectiveness and instructional flexibility, metacognitive teaching played an important role as an overlapping component of both constructs. / text