Since gaining independence in 2002, Timor-Leste has faced structural challenges in strengthening national development, particularly in improving human resources through education. This study examines the contribution of the Comunidade dos Países de Língua Portuguesa in the education sector toward the improvement of Timor-Leste’s Human Development Index during 2018–2023. Using a qualitative-descriptive approach, this research relies on secondary data collected from official reports of United Nations Development Programme, United Nations Children's Fund, World Bank, CPLP documents, and relevant academic literature. Data were analyzed through document analysis and content analysis, focusing on educational access, teacher quality, and individual capability development. The findings show that CPLP has contributed positively through teacher training programs, curriculum development, technical assistance, scholarships, and academic mobility schemes. These initiatives strengthened Timor-Leste’s educational institutions and human capital formation. Empirically, Timor-Leste’s HDI increased from 0.606 in 2018 to 0.634 in 2023, indicating gradual progress in human development. From the perspective of liberal institutionalism, CPLP functioned as an international institution that facilitated cooperation, reduced capacity constraints, and promoted mutual gains. However, challenges remain, including dependency on external assistance, linguistic barriers, limited domestic bureaucratic capacity, and unequal distribution of educational benefits. Therefore, long-term success depends on Timor-Leste’s ability to strengthen domestic institutions and ensure inclusive educational development.