OBJECTIVE: To assess the effectiveness of non-clinical interventions against acute respiratory infections and diarrhoeal diseases among young children in developing countries. METHODS: Experimental and observational impact studies of non-clinical interventions aimed at reducing the incidence of mortality and/or morbidity among children due to acute respiratory infections and/or diarrhoeal diseases were reviewed, following the Cochrane Handbook for Systematic Reviews of Interventions and the PRISMA guidelines. RESULTS: Enhancing resources and/or infrastructure, and promoting behavioural changes, are effective policy strategies to reduce child morbidity and mortality due to diarrhoeal disease and acute respiratory infections in developing countries. Interventions targeting diarrhoeal incidence generally demonstrated a reduction, ranging from 18.3% to 61%. The wide range of impact size reflects the diverse design features of policies and the heterogeneity of socio-economic environments in which these policies were implemented. Sanitation promotion at household level seems to have a greater protective effect for small children. CONCLUSION: Public investment in sanitation and hygiene, water supply and quality and the provision of medical equipment that detect symptoms of childhood diseases, in combination of training and education for medical workers, are effective policy strategies to reduce diarrhoeal diseases and acute respiratory infections. More research is needed in the countries that are most affected by childhood diseases. There is a need for disaggregation of analysis by age cohorts, as impact effectiveness of policies depends on children's age.