The Collaborative for Academic, Social, and Emotional Learning (CASEL) (2018) specified that "integrating SEL (Social-Emotional Learning) with instructional practices and academic content has become a growing priority" (p. 1). This priority originates from research that suggests SEL promotes positive student and long-term community outcomes, particularly in secondary schools. This canon of research, however, only reviews the outcomes of implementing purchasable curricula, not content-embedded SEL. The effectiveness of content-embedded SEL instruction, which comprises a large portion of how SEL is implemented at the secondary level (CASEL, 2018; Hart et al., 2013), cannot be effectively measured or predicted because there is little to no identified research regarding three essential factors: how teachers embed SEL, how teachers assess content-embedded SEL, and teachers' perceived readiness to embed SEL. The purpose of this research was to identify the methods secondary teachers indicate they use to implement and assess content-embedded SEL instruction and their perceived preparedness to do so. Educational leaders may be better able to evaluate the effectiveness of content-embedded SEL instruction and improve its implementation with this knowledge. Using a qualitative design, secondary teachers were interviewed to identify how they embed SEL into their instruction, how they assess SEL, and how prepared they perceive they are to deliver content-embedded SEL instruction. This research suggests that expectations for embedding and documenting SEL vary, but teachers appear to be implementing content-embedded SEL nevertheless. Furthermore, teachers recognize that pre-curated resources or lessons are provided to assist them in embedding SEL but appear to rely heavily upon their own teacher-created resources. Among these activities, teachers rely upon opportunities for reflection and choice and voice activities, but no one instructional strategy or manipulative was preferred overall. Teachers perceive student progress in SEL via observation of student behaviors, interactions, and responses both formally and informally. Regarding their preparedness to teach SEL, teachers perceive that their personal SEL proficiencies directly affect their abilities to teach them. Finally, teachers prefer experiential professional learning situations for SEL, and perceive that time to revisit and reflect in smaller, collaborative settings is an effective process for learning to implement SEL, including the use of specialists. / Doctor of Education / Social-Emotional Learning (SEL) is an improvement strategy that has gained popularity in the past decade. Results from research that suggest SEL develops beneficial student and long-term community effects have led to substantial efforts to spread SEL instruction, especially in middle and high schools. However, the research upon which these efforts are based only reviews the benefits of using purchasable programming, not SEL that teachers embed into their content. The success of content-embedded SEL, which makes up a large percentage of how SEL is employed in middle and high schools (CASEL, 2018; Hart et al., 2013), cannot be accurately measured or predicted because there is little to no identified information about three important factors: how teachers embed SEL, how teachers measure content-embedded SEL, and teachers' perceived readiness to embed SEL. The purpose of this research was to identify the methods middle and high school teachers indicate they use to embed and measure SEL and their perceived preparedness to do so. Educational leaders may be better able to measure the success of content-embedded SEL and improve its use with this knowledge. Middle and high school teachers were interviewed to identify how they embed SEL, how they measure SEL, and how prepared they perceive they are to embed SEL. This research suggests that expectations for embedding and recording SEL vary, but teachers still appear to be embedding SEL. Additionally, teachers understand that pre-curated resources or lessons are provided to assist them in embedding SEL but appear to rely more heavily upon their own resources. Among these activities, teachers rely upon opportunities for reflection and choice and voice activities, but no one teaching strategy was preferred overall. Teachers recognize student development in SEL via observation of their behaviors, interactions, and responses; they grade this development about half of the time. Teachers believe their personal SEL proficiencies directly affect their abilities to teach them. Finally, teachers prefer hands-on situations for learning how to embed SEL, and perceive that time to revisit and reflect in smaller, collaborative settings to be an effective process for learning to implement SEL, including the use of specialists.