This study investigates the determinants of tribal fertility through a cross-sectional analysis of 724 ever-married women residing in tribal-dominated regions of the Manipur valley, employing a cluster sampling method. Data collection spanned from April 2019 to November 2019. Employing classical statistical tests and binary logistic regression, this research explores various fertility indicators and identifies factors influencing the transition to a third birth. Results reveal a significantly higher fertility rate among tribal women (3.1) compared to non-tribal women (2.6). Lower levels of education (P<0.01), the sex of the second child (P<0.05), and the couple's desire for a specific number of sons (P<0.01) emerge as primary determinants influencing the transition to a third birth in this population.