This study determined the mediating effect of cultural intelligence on the relationship between leadership practices and school effectiveness. Purposive sampling was used in choosing elementary teachers, from selected public and private schools in Region XI, as respondents of the study. Three adopted questionnaires were validated and reliability tested using Cronbach Alpha. The descriptive - correlation design was used to determine the relationship among leadership practices, cultural intelligence and school effectiveness. Path analysis was also conducted to determine the mediating effect of cultural intelligence to the relationship of leadership practices and school effectiveness. Means, Pearson r, mediation analysis were applied to the data gathered. Results revealed that principals had a high level of leadership practices which means that these were always performed; cultural intelligence was high and was evident most of the time, while school effectiveness was very high and therefore was manifested most of the time. It also revealed that leadership practices, cultural intelligence and school effectiveness had significant relationships to all pairings of these variables. Mediation analysis result showed that cultural intelligence had a significant partial mediation on the relationship between leadership practices and school effectiveness which implies that cultural intelligence was only one of the factors on how leadership practices could influence school effectiveness.