Undergraduate field biology courses extend learning beyond the classroom by supporting students to learn biology through direct engagement, observation, and experimentation in the outdoors. Long a staple of natural sciences education, participation in field courses has been shown to improve students’ content knowledge and science affect while supporting their persistence in STEM and future employability. Although recent work has shown their influence on biology and ecology student outcomes, less is known about how field biology courses achieve these outcomes or how best to design field-based curricula. This dissertation addresses these gaps by investigating the role of campus-based undergraduate field biology courses with embedded research projects in shaping students’ experiences and outcomes. Chapter one introduces the historical and contemporary significance of undergraduate field science education, tracing its development, reviewing current pedagogical structures and associated student outcomes, and highlighting the modern pressures field courses face. Chapter two characterizes the breadth of undergraduate student outcomes through the thematic analysis of over 700 field journal reflections submitted by students in a campus-based undergraduate field biology course. Chapter three applies social network analysis to examine how student interactions with members of their professional and personal communities shift throughout a field course, showing that professional ties are positively associated with science identity. Through semi-structured student interviews, Chapter four explores how students’ intersecting identities shape their experiences in field courses, revealing both identity-affirming and identity-disaffirming processes. Chapter five implements mixed methods to quantify changes in students’ disciplinary “field biologist” identity across the duration of two campus-based field biology courses and identifies the instructional practices and contextual features that contribute to these shifts. Chapter six synthesizes this body of work and highlights potential areas of future investigation surrounding the improvement of undergraduate field biology pedagogy. Altogether, this dissertation demonstrates how undergraduate field biology courses function as critical spaces for social interaction and affective development in STEM. By highlighting how these courses influence students’ social and affective outcomes, this research enhances our understanding of field biology education and points toward strategies for designing effective field biology courses that support all students.