In “Student Aid, Student Behavior, and Educational Attainment,” we examine the US student financial aid system from the perspective of its impact on student choices and behaviors. We first acknowledge that individual responses to simple incentives like giving students more money when they enroll in more courses are important and should be implemented. We then turn to insights from behavioral economics and cognitive psychology that suggest that  such straightforward incentives may not be sufficient to generate the desired outcomes. When faced with difficult decisions, such as those involved in choosing among their postsecondary choices, students may choose the most salient option or the ones that requires the least effort, rather than the ones that would seem optimal from a rational point of view. This paper was written as part of a Gates Foundation project called "Understanding Student Behaviors: A Prerequisite to Supporting College Enrollment and Success".