In this book, the authors bring together in one place essential information about college students in the US in the 21st century. Synthesizing existing research and theory, they present an introduction to studying student characteristics, college choice and enrollment patterns, institutional types and environments, student learning, persistence, and outcomes of college. Substantially revised and updated, this new edition addresses contemporary and anticipated student demographics and enrollment patterns, a wide variety of campus environments (such as residential, commuter, online, hybrid), and a range of outcomes including learning, development, and achievement. The book is organized around Alexander Astin's Inputs-Environment-Outputs (I-E-O) framework. Student demographics, college preparation, and enrollment patterns are the "inputs." Transition to college and campus environments are the substance of the "environment." The "outputs" are student development, learning, and retention/persistence/completion. The authors build on this foundation by providing relevant contemporary information and analysis of students, environments, and outcomes. They also provide strategies for readers to project forward in anticipation of higher education trends in a world where understanding "college students in the United States" is an ongoing project. By consolidating foundational and new research and theory on college students, their experiences, and college outcomes in the US, the book provides knowledge to inform policies, programs, curriculum and practice. As a starting point for those who seek a foundational understanding of the diversity of students and institutions in the US, the book includes discussion points, learning activities, and further resources for exploring the topics in each chapter.