<p>This study primarily investigates the extent and degree of livelihood diversification among the plains and hill tribes in the Indian State of Assam. The study involves three Plains tribes, viz. Bodos, Misings, Mech Kacharis and three Hill tribes viz. Karbis, Dimasa Kacharis and Chakmas. Based on data collected from 1,086 sample rural tribal households, the degree of livelihood diversification has been evaluated by using the Simpson Diversification Index (SDI). This study demonstrates that while the degree of livelihood diversification varies among the hills and plains tribes, but the extent is greater among the plains. Monsoon-dependent farm-based livelihood involves risk and uncertainty. The cultivation techniques of hill agriculture are still primitive. Households with non-farm main activities other than services adopt farm-based activities simultaneously to ensure a steady supply of food and income. As a risk-mitigating approach, livelihood diversification across the farm and non-farm sectors has been the most commonly chosen option. The Tobit censored regression framework is employed to analyse the influence of geographical location on the likelihood of livelihood diversification. Findings indicates that the extent and degree of diversification differ according to geographical location. The study’s findings can help policymakers to design tribal development strategies that align with local livelihood patterns and cultural contexts.</p>