This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

Main objective

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.

Secondary objectives

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.