This study aimed to better understand the role that an undergraduate teacher exploration program for STEM majors played in STEM teacher education and recruitment. Utilizing journal data from 126 undergraduate students engaged in an intensive and immersive four-day internship that took place in Summer 2015 and Summer 2016, this study examined how the program's field experience developed students' socioemotional perceptions and social justice awareness. The field experiences took place at high-need middle and high schools in Los Angeles. With respect to socioemotional perceptions, findings show that STEM undergraduates who participated in the internship demonstrated insight about relating one-on-one with students, being caring and compassionate, establishing positive relationships, accommodating varying capabilities, and witnessing students and teachers supporting each other. Regarding social justice, participants expressed experiential understanding related to equity of learning opportunities, asset-based interpretive frames, recognition of privilege, and advocacy and activism. The field experiences allowed the STEM undergraduates to more deeply appreciate the importance of connecting with students, developing positive and constructive relationships with them, and reflecting on educational inequities confronting schools and students--a valuable foundation of teacher preparation for those who may choose to pursue a formal social justice-oriented teacher education program.