The main objective is to assess the effect of interventions to improve sanitation, hygiene, water quality and supply within low- and middle-income countries on child development.

The secondary objectives are to:

1. analyse any measured effect of water, sanitation and hygiene (WASH) interventions on school or preschool enrolment and attendance;
2. examine the feasibility of WASH interventions with regard to their implementation fidelity and participant compliance;
3. evaluate the effect of WASH interventions on intermediary outcomes of environmental contamination, gastrointestinal diseases and reduction in the burden of water collection and water costs; and
4. identify any adverse impact that WASH interventions may have for participants.