Chronic absenteeism is a widespread and troubling phenomenon affecting high school students nationwide. Existing research identifies an inverse link between student health and chronic absenteeism. Illness is a top cause of student absence, suggesting that school-based health services may play an important role in mitigating chronic absenteeism. Since 2014, a school-based health program which provides school nurses has been introduced in certain public high schools in Hawai'i. Using a merged panel of school-level directory, enrollment, chronic absenteeism, graduation rate, and program participation data from the 2010-11 to 2018-19 academic years, we estimate how the program impacted high school chronic absenteeism. Using a synthetic control method approach, we find that school-based health programs reduced overall chronic absenteeism two years and three years following program adoption. Sensitivity analyses (i.e., including leave one out exercises and alternative combinations of predictor variables) highlight the robustness of these findings. These results demonstrate the potential for school-based health services to reduce chronic absenteeism among high school students.