BACKGROUND: Modifications made to the Kilifi Developmental Checklist and the psychometric characteristics of the new measure (The Kilifi Developmental Inventory) which assess the psychomotor functioning of children aged 6-35 months are described. METHODS: Two groups of community children (319 rural and 104 urban dwellers) and nine children with neurodevelopmental disorders were recruited for a cross-sectional study. RESULTS: In both a rural and urban reference population, the inventory showed excellent internal consistency, interobserver agreement, test-retest reliability and sensitivity to maturational changes. Children with neurodevelopmental impairment and those who were underweight had significantly lower scores than the community sample, attesting to the sensitivity of the measure. Mothers found the assessment procedures acceptable and informative. CONCLUSIONS: The Kilifi Developmental Inventory is a culturally appropriate measure that can be used to monitor and describe the development of at-risk children in resource-limited settings in Kenya.