The purpose of this qualitative descriptive study was to explore how upper elementary and middle school teachers describe their preparation experiences and instructional practices in teaching STEM to ELLs. This study was guided by literature and Geneva Gay's (2021) Culturally Responsive Teaching Practices conceptual framework. The research questions in this study were RQ1: "How do upper elementary and middle school teachers describe their preparation experiences in teaching STEM to ELLs?" and RQ2: "How do upper elementary and middle school teachers describe their instructional practices in teaching STEM to ELLs?". The methodological approach for this study was a qualitative descriptive study with purposive sampling. Twelve teachers participated in one-on-one semi-structured interviews, and eight non-overlapping participants in two focus groups. The data collected were analyzed using Braun and Clarke's (2022) 6-phase thematic analysis. The findings of this study suggest that teachers of STEM to ELLs generally lack the required training to teach STEM to ELLs but have various life experiences that have helped shape how they teach. Additionally, the study's findings suggest that a hands-on, exploratory, and student-centered approach coupled with many opportunities for peer discussion and collaboration to teach STEM to ELLs is effective. The results highlighted the importance of training and ongoing support for preservice and in-service teachers of STEM to ELLs. [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.]