Creating learning environments and learning experiences for students is one of the primary purposes of student services. Student services professionals need to have a solid understanding of the cognitive development of college students in order to design activities that will enhance that development. This issue of New Directions for Student Services reviews five theories of the cognitive development of college students and explores the applications of those theories for student affairs practice. The theories shed light on gender-related patterns of knowing and reasoning, interpersonal, cultural, and emotional influences on cognitive development, and people's methods of approaching complex issues and defending what they believe. This is the 88th issue of the quarterly journals New Directions for Student Services.