The purpose of this phenomenological study was to explore the perceptions of experienced STEM teachers regarding STEM preparedness and implementation at a South Texas elementary school for grades kindergarten-five (K-5). This qualitative study used a phenomenological framework. The site for this study was a South Texas elementary school currently in year three of STEM implementation. The researcher identified 10 participants that shared insights into their educational and personal backgrounds, STEM instruction related experiences, and their readiness for STEM instruction implementation. The study's intent was to build on existing literature supporting knowledge on STEM integration and sustainability by exploring STEM educator preparedness and professional development for the implementation of STEM education. Implications from this study suggest that a STEM culture can be developed and sustained at the school level. A well-structured STEM program included an established culture of STEM, evidence of a rigorously designed professional development structure, an emphasize on STEM as a pedagogical practice and the collaborative efforts of all stakeholders. [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.]