The debate about the nature and role of teacher professionalism in teacher education contexts has a long history but little research has been conducted in small island states of the Caribbean, especially focused on the understanding of prospective teachers. Therefore, this interpretive descriptive study engaged 16 prospective teachers from a teacher preparation program in Trinidad and Tobago to explore their perceptions and experiences about conceptualizing and operationalizing the construct of teacher professionalism. The conceptual framework was based on Hargreaves' ages of professionalism theory and Dweck's mindset theory. The three main research questions that guided the study focused on prospective teachers' perceptions of themselves as emerging teacher professionals, prospective teachers' descriptions of the experiences that contribute to the development of their ideas on teacher professionalism, and prospective teachers' operationalization of the construct of teacher professionalism. Data collection tools included 16 individual participant diaries and semi structured interviews. Thematic coding was employed for data analysis. The key findings of the study were that prospective teachers have clear but incomplete views on the nature and characteristics of teacher professionalism, which they have gained from personal experiences, not from the teacher training process. Supporting findings confirmed the growth mindset of the prospective teacher participants and their focus on unprofessional behaviors when describing teacher professionalism. The findings have potential implications for positive social change through improvements to teacher training practices that include the understanding of informally learned views of teacher professionalism. [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.]