Acute respiratory infections (ARI) are leading killers of children. Case management using community health workers (CHW) has halved ARI mortality in children in Asia. WHO/UNICEF recommend integrating pneumonia into Home Management of Malaria strategies. However, in sub-Saharan Africa, CHW's performance to recognise pneumonia is rarely demonstrated. We evaluated the ability of CHWs to assess rapid breathing in under 5 year olds and explored caretaker interpretation of pneumonia symptoms. Ninety-six CHWs were evaluated for their skills to count and classify breathing rate in inpatient children. Respiratory illness concepts and actions were obtained from focus group discussions with mothers, video probing and key informant interviews. Of the CHW assessments, 71% were within +/-5 breaths/min from the gold standard. The sensitivity of CHW classification was 75% and the specificity was 83%. Many local terms existed for ARIs, such as "quick breathing" and "groaning breathing". There was consistency in the interpretation of severity, cause and treatment, most being related to fever and treated with antimalarials. Given the ability of CHWs to classify pneumonia, their skills should be tested in real life. To minimise failure to treat and overtreatment, context-specific communication strategies that improve care-seeking and increase illness prevalence among patients assessed by CHWs are needed. A toolkit including a set of methods for this purpose is proposed.