Three teachers, who held extreme preferences for the ways they learn, participated in a year-long professional development course, designed to sensitize teachers to their own and colleagues' individual learning differences (ILDs). The case study focuses on their extreme learning preferences and discusses the impact of these preferences on their language, beliefs and practice, both before and after the course. The teachers' learning preferences were determined from their scores on seven learning/cognitive styles tools and understood further from field notes, interviews and pre-/post-test responses. The study suggests that teachers with extreme learning preferences tend to: (a) teach the way they prefer to learn; (b) overgeneralize and project their own learning needs onto students; and (c) hold initial pathognomonic ("blame the learner") beliefs about students mismatched to them. After the course, the teachers changed their language, beliefs and practice in the direction of becoming more effective teachers, e.g., they held more interventionist beliefs ("I can intervene to help the learner"). The three teachers were strong prototypes who can provide insights about the importance of ILDs in learning, practice and professional development. (Contains 6 tables.)