The number of Nigerian graduate students enrolling at HBCUs has increased over last decade. Nigerian students have consistently made-up majority of the student population enrolled in U.S. colleges from West African countries. However, despite the growing presence of Nigerian students at HBCUs, these students face several adjustment challenges while pursuing their graduate degrees. These challenges often lead to frustration in adjusting to the new academic environment. This qualitative study explored the adjustment challenges of Nigerian graduate students at one four-year Historically Black College and University (HBCU) located in Maryland. The study also examined Nigerian students' coping strategies in adjusting to the academic, social, and cultural environments of U.S. higher education. The study used the Schlossberg's Transition Theory to help make meaning of the Nigerian graduate students underlying issues in transitioning and adjusting to higher education environments. The data collection process of this phenomenological qualitative study was achieved through in-depth interviews with 10 Nigerian graduate students at one-four-year HBCU in Maryland. Semi-structured interviews with open-ended questions were conducted using thirteen guiding interview questions. During the data analysis, common themes of participants lived experiences emerged. Existing literature review revealed that the adjustment challenges of international students to the U.S. higher education institutions have remained almost the same over the past decade. The study found that Nigerian graduate students encountered challenges related to different academic styles, negative emotions, culture shock, financial challenges, and a lack of awareness about institutional support services. The study also found that these students utilized family and peer support system as the effective coping strategies in adjusting to the U.S. higher education system. It is recommended that higher education administrators and advisors need to provide support services that meets the specific needs of their international students. Administrators and faculty will make informed decisions if they are sensitive to the needs of their international students by providing support services that will aid in their transition. International students might equally ease their transition by taking advantage of the available support services provided by their institution in adjusting to the new academic, social, and cultural environment. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]