In an attempt to increase high school students' sexually transmitted disease (STD) testing rates, the Centers for Disease Control and Prevention's Division of Adolescent and School Health partnered with ICF and Chicago Public Schools to adapt and implement the "GYT: Get Yourself Tested" health marketing campaign for a high school. Clinic record data and student retrospective self-report surveys (n = 193) tested for differences between the GYT intervention school and a comparison school on a number of outcomes, including human immunodeficiency virus and STD testing. Clinic record data showed that testing increased significantly more for the intervention than the comparison school during the GYT implementation period (B, 2.9; SE, 1.1, P < 0.05). Furthermore, the odds of being tested at the referral clinic were more than 4 times (odds ratio, 4.4) as high for students in the campaign school than for those in the comparison school (95% confidence interval, 2.3-8.2). Survey data did not show increased self-reported testing but, more students in the GYT school (92.7%) were aware of where to receive free, low-cost, or affordable human immunodeficiency virus and STD testing than students in the comparison school (76.0%; P < 0.01). Among sexually experienced students (n = 142), significantly more from the campaign school reported that they intended to test for STDs in the next 3 months (48.4% strongly agree and 33.2% agree) compared with those at the comparison school (27.4% strongly agree and 32.9% agree; P < 0.05). Our pilot suggests that a student-led GYT campaign in high schools may successfully increase STD testing of students. Although some of the findings from this pilot evaluation are promising, they are limited, and broader implementation and evaluation is needed. Future evaluation efforts can include more rigorous study designs, multiple schools or districts, longer campaign and evaluation across an entire school or calendar year, or in combination with other school-based testing strategies like a mass school-based screening event.