This full research paper focuses on a systematized review of the literature on low-socioeconomic students in engineering. Increasing the diversity of engineering cannot be addressed without acknowledging the necessity for equity across socioeconomic groups. An important step to developing equitable pathways that allow low-socioeconomic students to engage in engineering education is by identifying barriers to participation. Because little is known about the 'invisible' population of engineering, a literature review regarding low-socioeconomic students' participation in the larger STEM education context provides an opportunity to begin making the population visible. This work identifies barriers that may make participating in engineering difficult and provides suggestions for researchers and practitioners to work to remove them.