My study contributes to the literature that examines diverse issues pushing back on and expanding Social and Emotional Education in elementary school contexts. Schools and educational institutions require more attention and responsibility to promote students' social, emotional, and relational lives. In my dissertation, I paid particular attention to everyday classroom interactions between first graders that took place away from the eyes and ears of teachers and explored how they engage in facilitating social and emotional practices and relationship building in these daily moments of classroom underlife (Goffman, 1961). Drawing upon CASEL's five core domains of SEL competencies (CASEL, 2020) and a languaging theory (Bloome & Beach, 2019), my microethnographic discourse analysis examined what social, emotional, and relational aspects were demonstrated and constructed in their underlife interactions and what interactional moves the students made that fostered social and emotional practices and relationship building. My findings show that (a) the students demonstrated and built up all of the CASEL's five core domains of SEL competencies in momentary classroom underlife interactions, and (b) they utilized tactful and sophisticated interactional moves (e.g., relational keys) to explore and construct various social norms and relationships with each other and the world while meeting expectations for classroom tasks.My findings highlight how the students fluently demonstrated and built each of the CASEL's five core domains of SEL competencies in an integrated way in fleeting moments of classroom underlife interactions. Moreover, my findings emphasize that the first graders are already doing the sophisticated social, emotional, and relational work in their underlife that constitutes an essential part of their everyday classroom lives. These findings challenge the dominant Social and Emotional Education approach the teaching of SEL knowledge and skills is explicitly mapped out discretely and sequentially. These findings also raise fundamental questions about the dominant discourse in SEE in which schools must explicitly teach SEL knowledge and skills to promote students' social, emotional, and relational wellbeing. Additionally, my study reilluminates the everyday moments of classroom peer interactions that are often neglected as off-task or side talk in a space with rich potential to foster social and emotional practices and relationship building. I argue for a shift from viewing these underlife interactions as irrelevant and interrupting to viewing them as necessary and enriching. Moreover, I argue that educators should acknowledge and encourage these underlife interactions as an important way of promoting students' social, emotional, and relational wellbeing in the classroom. Furthermore, a discourse analytic approach to SEE research allowed me to produce transcript-level examples of student underlife interactions; I argue that young children are social actors who can enrich their classroom lives for and by themselves, socially, emotionally, and relationally, through languaging relations in classroom underlife interactions. I also argue that paying attention to everyday underlife interactions is essential to understanding and encouraging students' diverse social, emotional, and relational experiences and practices in the classroom.Such an understanding can assist educators and educational researchers in acknowledging multiple pathways to promote social and emotional practices and relationship building. In addition, viewing everyday classroom peer interaction as a rich sight of fostering social and emotional practices and relationship building helps attend to and identify what young children are already doing in the frequently backgrounded or dismissed classroom interactions. This perspective also highlights to consider ways to create humanizing and ethical classroom spaces where teachers learn with and about students to improve their daily classroom experiences. In a current educational climate that tends to stigmatize culturally and linguistically diverse students in social, emotional, and relational domains (Mahfouz & Anthony-Stevens, 2020), my research that examines young culturally diverse children's sophisticated and strategic languaging contributes significantly to a relational and ethical approach to SEE. Finally, considering the widely used CASEL frameworks in SEE, where collaboration is an important pillar, my research, which centers on students' practices, experiences, and needs in the social, emotional, and relational domains, is imperative. [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/en-US/products/dissertations/individuals.shtml.]