Background: The world's aging is a global phenomenon. The active aging framework responds to this phenomenon by emphasizing on the connections between good health, participation, and security in the lives of older people. Objectives: This study developed a novel measurement of active aging for older people by integrating the international concept with specific features of Thailand. Materials and methods: Active aging measurement components were generated through relevant literature reviews, with content validity examined by experts. Internal consistency and test-retest reliability were used for examining measurement reliability. Two hundred older people living in Chiang Mai Province participated in a pilot survey. Results: The active aging measurement was composed of four components including health, social participation, security, and enabling an environment for active aging. Good internal consistency was represented overall by Cronbach’s alpha=0.77, while the test-retest reliability value was 0.89. Conclusion: The active aging measurement was developed for older people. It is a valid and reliable measure of an active aging index.