Given the important role of the CPH in policy planning and research, this study aims identify and implement set of approaches for harmonizing the 1970–2020 Philippine census dataset, enabling longitudinal analysis and the detection of data patterns over time. The output of this research is a more consistent data source on the Philippine censuses that will contribute to research with better informed insights on the population and policy recommendations. The study also aims to document the harmonization process and develop recommendations for future Philippine census data collection and harmonization.