The summer after high school graduation is a largely unexamined period of college access among underrepresented populations in higher education. Yet, during this period students encounter a range of informational, financial, and other barriers to enrollment, while at the same time they no longer have access to school counseling, have yet to engage with their college community, and may come from families with little college-going experience. We report on two experimental studies – one conducted in Boston, MA and one conducted in Fulton County, GA – in which we offered summer college counseling to high school graduates who had indicated their intent to enroll in college in the fall following high school graduation during Summer 2011. Financial aid advisors or high school guidance counselors offered to help randomly selected groups of students review financial aid award letters; secure additional funding; and access, digest, and complete required college paperwork. Across both sites, we find that offering students two to three hours of support during the summer months increases on-time enrollment rates by approximately three to five percentage points. In Boston, this effect was driven largely by inducing students in the treatment group to attend community colleges, which may reflect the priorities of the organization providing the outreach to ensure that students were pursuing financially affordable postsecondary options. In Fulton County, GA, the effect was driven primarily by inducing low-income (as measured by free/reduced price lunch status) students to enroll on-time in four-year institutions. The interventions cost approximately $100 – $200 per student. Simple cost-benefit comparisons suggest that, relative to offering students additional financial aid, mitigating summer attrition is a highly cost-effective approach to increasing college access among low-income high school graduates. While college enrollment outcomes will not yet be available at the time of the conference, we will further report on implementation findings from a set of Summer 2012 experimental interventions designed to assess the impact of peer college mentors, high school counseling, outreach from postsecondary institutions and digital messaging (i.e., text messaging) on timely college matriculation among college-intending high school graduates.