Acute respiratory infections cause mortality in young children. We assessed the effects of water, sanitation, hygiene (WASH) and nutritional interventions on childhood ARI. Geographic clusters of pregnant women from rural Bangladesh were randomly assigned to receive 1) chlorinated drinking water and safe storage (W); 2) upgraded sanitation (S); 3) handwashing promotion (H); 4) combined water, sanitation, and handwashing (WSH); 5) nutrition intervention including lipid-based nutrient supplements; 6) combined WSH plus nutrition (WSHN); or 7) no intervention (control). Masking of participants was not possible. Acute respiratory illness was defined as caregiver-reported persistent cough, panting, wheezing, or difficulty breathing in the past 7 days among index children, those born to enrolled women. We assessed outcomes at 12 and 24 months of intervention using intention to treat. Compared with children in the control group (ARI prevalence, P: 8.9%), caregivers of index children reported significantly lower ARI in the water (P: 6.3%, prevalence ratio (PR): 0.71; 95% CI: 0.53, 0.96), sanitation (P: 6.4%, PR: 0.75, 95% CI: 0.58, 0.96), handwashing (P: 6.4%, PR: 0.68, 95% CI: 0.50, 0.93), and the combined WSH+N arms (P: 5.9%, PR: 0.67, 95% CI: 0.50, 0.90). Those in the nutrition (P: 7.4%, PR: 0.84, 95% CI: 0.63, 1.10) or the WSH arm (P: 8.9%, PR: 0.99, 95% CI: 0.76, 1.28) reported similar ARI prevalence compared with control children. Single targeted water, sanitation, and hygiene interventions reduced reported respiratory illness in young children. There was no apparent respiratory health benefit from combining WASH interventions.