Increasing the diversity of the STEM workforce has been an issue of national concern for decades. African American and Latino students, from working class families, are significantly underrepresented in science and technical fields, and this is especially the case for female students within computer science and engineering. Over half of first generation, lower-income Latinos and African American students use two-year colleges, or trade colleges, as an entry point to the four-year degree, but so few actually complete these pathways. Thus, research is warranted to better understand the experiences of ethnically diverse working class women and men within these complex pathways. My research, guided broadly by an ecological perspective that highlights the importance of macro-economic factors and multiple contexts (e.g., home, school, and work), has focused on the mentoring experienced by lower-income students as they strive to “get on track” and persist toward a four-year STEM degree. Drawing upon longitudinal survey and interview data with high school students, trade college students, community college, and university students, I have investigated how particular functions of mentoring are associated with STEM persistence. I will describe examples of essential instrumental functions of mentoring and productive mentoring constellations, articulate a need for greater organizational infrastructures for mentoring, and point to implications for designing mentoring interventions, governmental aid for students pursuing higher education, and transfer program designs that link shorter-term certificate and degree programs to four-year degree programs.