The significance of mathematical creativity cannot be undervalued. Encouraging creativity in learning can increase student rigor, foster greater learning engagement, and promote a thirst for knowledge both inside and outside of school. However, researchers have identified that research on mathematical creativity has not been foregrounded. Complicating the issue, although teachers may recognize the importance of teaching for creativity in theory, they often struggle to implement it in practice. Therefore, studying the mathematical creativity of teachers is vital to understand the extent of their creative thinking and how their mathematical meanings aid their engaging with mathematics creatively. In this dissertation study, I report on the mathematical creativity of 8 secondary preservice teachers (PSTs) in the context of teaching experiments involving quadratic growth. I specifically situate PSTs' mathematical creativity against the backdrop of their meanings for quadratic growth. In doing so, I describe PSTs' mental operations in conceiving meanings for quadratic growth and establish a connection between these mental operations and their mathematical creativity using a cognitive lens. From my analysis, I identified a general sequence in the PSTs' conceptions of quadratic growth. The sequence entails PSTs encountering a perturbation regarding the nature of growth of 2-D growing rectangles, conceiving increasing amounts of growth in quantities, and conceptualizing quadratic growth as entailing constantly changing amounts of change. Regarding mathematical creativity, the PSTs demonstrated the major criteria for mathematical creativity, namely novelty, flexibility, plausibility, and mathematical foundation. I identify two forms of flexibility: representational flexibility and reversible reasoning and two forms of novelty: contextual novelty and novelty resulting from accommodation. My study reveals variations in the extent to which each PST exhibited all criteria for mathematical creativity. Furthermore, it emphasizes supporting PSTs' meanings and representations, whether normative or non-normative, to foster their conceptual understanding and promote their mathematical creativity. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]