An integral part of all initial teacher education programs is the school-based practicum where pre-service teachers get an opportunity to develop their teaching skills and knowledge in a classroom setting. Many have suggested that these experiences are very powerful in shaping pre-service teachers' views of teaching because they are perceived as being "real" as opposed to the "artificial" environment of the tertiary courses. This can mean that the practicum experiences can legitimate or negate the learning of the tertiary courses. In particular, pre-service teachers can make significant positive changes in their affective responses to mathematics, but the longevity and stability of these changes can be challenged through their school-based practicum experiences. (Contains 3 notes and 2 tables.)