Because federal financial aid guidelines stipulate that students must be enrolled in a minimum of 12 credits per semester in order to receive the full amount of aid, many colleges and universities define full-time enrollment as 12 credits per semester. Yet, if a student takes only 12 credits each fall and spring term, it is impossible to complete an associate degree in four terms or a bachelor's degree in eight. The fact that students can be enrolled full-time and still not graduate on time is one reason why it takes students so long to complete degrees. In recognition of the importance of on-time completion, a number of institutions, states, and higher education advocacy groups have identified the redefinition of full-time as 15 credits per semester as a crucial strategy for improving college completion rates. This report provides an overview of the types of 15-credit strategies being used nationally, the research evidence on their effectiveness, and their potential challenges and unintended consequences. The report also identifies additional policies that facilitate higher intensity enrollment without focusing exclusively on 15 credits. [Funding for this report was provided through the Guided Pathways to Success project led by Complete College America and supported by Lumina Foundation.]