This study examined the effect of teacher professional learning community (PLC) dimensions on students' social and emotional learning (SEL) using a structural equation modeling (SEM) approach. An explanatory sequential mixed-method design was employed. In the first stage, 12 woredas were randomly selected, and 12 senior secondary schools were chosen using a multi- stage sampling technique, with a sample size of 397 teachers. Data from these teachers were analyzed using SPSS 27, and the results showed excellent internal consistency for both the SEL (α = 0.937) and PLC (α = 0.920) scales. In the second phase, a qualitative case study design was utilized, employing extreme case sampling to explore outlier cases with extreme PLC and SEL scores. Semi-structured interviews were conducted with ten teachers, and thematic analysis was applied to the qualitative data. The findings revealed that students' SEL competencies, particularly self-management and self-awareness, were moderately developed, but responsible decision-making needed improvement. A multifaceted approach to SEL, involving diverse teaching methods and strong teacher-student relationships, was essential for fostering these competencies. However, inconsistent implementation and resource constraints hindered the effectiveness of SEL interventions. Teachers engaged positively in PLCs, but the direct impact on SEL outcomes was limited due to challenges such as time constraints and resource limitations. Shared and supportive leadership, trust, and collegial relationships were key factors for successful PLC implementation. The study concluded that integrating SEL principles within PLC frameworks and investing in continuous professional development are critical for enhancing students' SEL skills. Thus, the schools must invest in continuous professional development that integrates SEL principleswithin PLC frameworks. Key words: professional learning community, social and emotional learning, teachers collaboration, student competencies, and structural equation model