Purpose: The purpose of this case study was to reflect the essence of the lived experience of 10 elementary school teachers in Southern California as they integrate social-emotional learning (SEL) into the instructional day with the Recognize, Understand, Label, Express, and Regulate (RULER) Approach. Conceptual Framework: The conceptual framework for this case study was the Collaborative for Academic, Social, and Emotional Learning (CASEL) framework of social-emotional competencies (SECs) and the RULER Approach Theory of Change (ToC). Methodology: A phenomenological design was used to explore and analyze the essence of the lived experiences of 10 elementary school teachers in Southern California as they integrate SEL into the instructional day with the RULER Approach. The CASEL framework of SECs was used to organize questions and data analysis, and the RULER Approach ToC served as the theoretical grounding for SEL. The selection of the location and sample was purposeful. Data were collected through one-on-one, semistructured interviews to gain insight and perspective into the teachers' lived experience. Findings and Conclusion: The review of transcripts led to significant statements that were coded under the five initial codes. From these codes the researcher derived four themes represented by 16 formulated meanings, all of which were evidenced by statements of the research subjects. The overall essence of the elementary teachers' experience of integrating social-emotional learning into the instructional day with the RULER Approach was described. The results of the study yielded four key themes supported by the literature and the data collected: (a) environmental factors that supported implementation, (b) a change in teaching practices and behaviors, (c) an internal shift in teachers' general sense of being, and (d) far-reaching personal benefits. Recommendations: Teachers are experiencing high levels of stress and occupational burnout, but the participants of this study revealed that through the practice of SEL implementation during the instructional day with the RULER Approach, they were able to develop skills that buffer the impact of professional stress. Future research should be conducted to explore the themes that emerged in this study more closely using a variety of methodologies and frameworks to further refine the outcome of this study. [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.]