First-generation students are estimated to be a large portion of current and future postsecondary education enrollment in the United States. Additionally, existing research indicates that those students are more likely to be at risk of not being as successful in higher education. However, all this research is in spite of the fact that there is not a nationally agreed on definition of what is a "first-generation student." This study uses two large national data sets of individual student course records and registration from the past two decades, gathered from 140 different U.S. institutions, to examine how institutions are gathering data on and defining first-generation students, the intersectionality of first-generation students with other student populations that have been traditionally underserved in U.S. postsecondary education, and the success of those intersectional students at their various institutions. Results indicate the high level of intersectionality of first-generation status with other student populations that have traditionally been underserved in U.S. postsecondary education, the contribution of first-generation status to the increased likelihood of a student being less successful in higher education, and the compelling need for a national standard for reporting the results of a large student population that is at greater risk. The need for creating a greater focus on the inequitable outcomes experienced by an extremely large percentage of postsecondary students is discussed.