BackgroundContent validation is a process of obtaining evidence from experts to ensure that the domains or the message of a measurement tool or educational material performs its intended purpose. This study describes the validation of developed educational materials (poster, leaflet and song), which are available in local languages for health education on maternal depression in Ibadan, South-West, Nigeria. MethodsThis cross sectional study used experts’ judgement and clients’ evaluation. Six experts and 50 maternal-child health clients for each material participated. Suitability Assessment of Materials (SAM) tool and its Yoruba translated version were used by the experts and the clients respectively. The outcomes include Cronbach alpha coefficient ≥ 0.8, Item level- Content Validity Index (I-CVI) ≥0.78, Scale – Item Content Validity/ Universal Agreement (S-ICV/UA) ≥ 0.8, interclass coefficient (ICC)0 ≥0.7, and the proportion of of rating of suitability assessment of material among clients. Reliability test, calculation by formula. descriptive statistics and Fisher exact were used respectively for the statistical analysis with SPSS version 25. ResultsThe mean age of the experts was 41.6±7.2 years and that of maternal child health clients was 30.7±5.4 years for poster, 31.3±5.2 for leaflet and 29.0±5.1 for song. Cronbach alpha reliability coefficient of the translated SAM were; 0.69 for poster, 0.87 for leaflet and 0.20 for song. The Interclass Coefficient (ICC) of all the materials were; leaflet (0.97); poster (0.89); song (0.98) and the internal consistency Cronbach alpha coefficients >0.8. The validity index for the materials were; leaflet (0.94), poster (0.94) and song (1.00). The Item Scale Level Universal Agreement (S-ICVI/UA) was >0.8 for all the materials. Nearly all clients (96%) rated song content as superior. The poster and leaflet were rated as superior by 74% and 68% of clients respectively. Clients rated the content, literacy demand and cultural appropriateness domains as superior regardless of their sociodemographic characteristics. ConclusionThese locally developed education materials for maternal depression have excellent content validity of experts and were highly rated by clients. This process should inform the development of content of other education materials in Africa.