Teachers' beliefs and attitudes are important for understanding and improving teacher effectiveness. This study focuses on the extent to which teachers hold constructivist beliefs and the role such beliefs may play in creating a student centered instruction, focused on students´ interests and motivations. Using a mix of quantitative and qualitative analysis the study examines the extent to which Chilean teachers exhibit constructivist beliefs and how those beliefs differ between the pre-service period and the early years of teaching, an area in which there has been little research in Chile. The study uses data from a sample of 101 beginning teachers in 2013 who were first surveyed in 2010 when they were in the last years of their teacher education programs. It finds that teachers' orientation towards constructivist beliefs decrease from pre-service into the first years of teaching. Yet despite this general decrease in beliefs, there are differences in the results among groups of teachers who differ in their background characteristics, initial teacher training characteristics, characteristics of the school in which they start teaching, and teachers' beliefs. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]