This qualitative case study examines teachers' implicit meaning systems built around their core beliefs on the malleability of human qualities. Previous research has demonstrated the influence of students' implicit theories on motivation and achievement and has presented successful interventions for students. However, research on teachers' implicit theories and, in particular, their actualization in natural environments is lacking. The data for this study include observations and stimulated recall interviews with two Finnish teachers whose opposing implicit theories were first indicated in 2000 by Carol Dweck. The results depict how these teachers' implicit meaning systems influence their ways of interpreting students' behavior, learning, and achievements, which in turn guide teachers' pedagogical thinking as well as their practices for motivating the students. However, these Finnish teachers' implicit theories also appear to be intertwined with culture-bound assumptions, and the classroom implementation of these theories was observed to vary situationally.