This chapter discusses diseases that commonly kill children. It covers, causes, priorities, and community-based and clinic programmes, including immunization and the Integrated Management of Childhood Illness (IMCI). It emphasizes ways in which diarrhoea, pneumonia, and malaria can be managed at community and family level. It highlights the dangers and types of diarrhoea, its causes, and treatment. It includes a detailed section on dehydration and oral rehydration therapy (ORT and ORS), appropriate rehydrating foods, and how these can be embedded into use by families. It describes acute respiratory infection (ARI), its causes, prevention, diagnosis, and treatment. Importantly, it describes how community health workers (CHWs) and community members can assess ARI severity and how it can be best treated, including the careful use of community-based and home-based antibiotics in remoter areas. Finally, the chapter addresses malaria diagnosis and treatment, particularly how a community can set up a step-by-step control programme.