Though limited, research suggests school-based water, sanitation and hygiene (WASH) improvements are capable of reducing pupil absence from 35-42%. However, few studies have rigorously evaluated the impact of comprehensive WASH in Schools (WinS) improvements on pupil absenteeism; to date, no research on the impact of WinS has been conducted in Lao PDR. This study will use longitudinal data collection to quantify the impact of UNICEF's WinS program on pupil learning and health in Lao People's Democratic Republic (Lao PDR).