Efforts to integrate socially-relevant issues in science education is not a new idea. However, socio-scientific issue (SSI)-based teaching has created challenges in emphasizing the interrelationships among subject matter with the goal of creating scientifically literate citizens. Another challenge relates to how to introduce the ideas to prospective teachers as well as the pedagogical strategies for teaching SSIs; addressing this challenge was the focus for this study. The inquiry in this mixed methods study focused on one overarching question: To what extent does a case-based learning environment (CBLe) influence prospective elementary teachers conceptualization of socio-scientific issues (SSIs) and SSI-based teaching?An instructional design framework was developed for a case-based learning environment and implemented in a science methods course for early childhood education prospective teachers. The participants (four primary and twenty-two secondary) engaged in several activities for four cases such as participating in online and classroom discussions and writing reflection papers. The participants also engaged in an example SSI activity for an elementary classroom, and worked as a group to develop their own instructional resource designs about a SSI of their choice. Finally, the prospective teachers presented their instructional resources to the class and wrote individual reflections for their designs.Data from the study documented the participants evolution of socio-scientific reasoning (SSR) skills, conceptualization of SSIs and SSI-based teaching, as well as their planning after engaging in the designed CBLe. The analysis of the participants pre- and post-Socioscientific Issue Questionnaire (SSIQ) scores revealed that participants post-SSIQ scores were statistically significantly higher than pre-SSIQ scores for three of the four constructs of SSR (i.e., complexity, inquiry, perspectives). Four primary participants online discussion posts and reflections for cases supported that engaging in case-based learning experiences enhanced prospective teachers conceptualization of SSIs, SSR skills, confidence to teach SSIs, and appreciation of the purposes of SSI-based teaching. Finally, the findings suggested that the primary participants advanced their conceptualization of SSI-based teaching after the planning activity. Implications for research and practice, suggestions for curriculum designers and science educators, and future research directions are explored.