Using a framework of colonization in science, technology, engineering, and mathematics (STEM), this U.S.-based study examined how seven Native American PhD students/ postdoctoral scholars experienced impostor phenomenon. Participants were identified/ contacted at a national conference on minorities in STEM through purposeful sampling. Surveys computed impostor phenomenon scores on a validated scale, while interviews documented how identity and culture contributed to impostor phenomenon in academia. Using a phenomenological approach, interviews were analyzed inductively using a constant comparative method. Surveys scores indicated high to intense impostor phenomenon. Interviews with the same participants further identified the following aspects of impostor phenomenon in relation to their minoritized identity: cultural differences and lack of understanding of Indigenous culture, lack of critical mass and fear of standing out, academic environment, family background and upbringing, and looks and diversity status. Developing a diverse and culturally competent STEM workforce requires a deeper understanding of what deters Native American individuals from pursuing a STEM career. They have the lowest college enrollment and retention rates compared with any race in the United States and could be vulnerable to racial bias and discrimination. Understanding impostor phenomenon through culturally relevant experiences would be crucial to broaden participation in STEM careers.