This chapter suggests strategies for recruiting hard-to-reach adolescents and emerging adults, in particular, low-income, immigrant, ethno-racial minorities, first-generation college students, undocumented students, unhoused, and LGBTQIA+ youth. Developing trust and providing empathy, compassion, and respect are essential for recruiting these vulnerable populations who have often experienced discrimination, legal consequences, inequities, and even violence that have eroded their belief in democracy, meritocracy, and social justice. Long-term collaborations with families, community centers and organizations, clubs and youth-led organizations, schools, universities, and other places frequented by youth are essential for recruiting these hard-to-reach populations. In addition, random sampling is seldom possible with these vulnerable and transient youth, so snowball sampling, flyers, word-of-mouth, establishing a presence in neighborhoods, providing stipends, and creating safe spaces for data collection are also essential and will ensure that theory and research address the development of hard-to-reach adolescents and emerging adults.