Open Journal of Forestry, 11, 254-291.Land degradation due to use of unsustainable agricultural practices has af- fected many communities in rural mountain areas rendering them to be more vulnerable to income poverty and inequality. In this case, agroforestry sys- tems promise to offer great solutions as they can be developed in unfavour- able conditions where other production systems would either rapidly degrade the land or otherwise would not be possible. However, little is known whether agroforestry can address issues of income inequality in mountain areas. Hence, we conducted a study to investigate the nature and determinants of income inequality in Uluguru Mountains, Tanzania. Specifically, we used the cross-sectional research design and we calculated the income percentile shares, Gini coefficients and the coefficient of variation (CV), to pinpoint the nature of income inequality in the study area. The determinants of income inequality were analysed using the step by step multiple linear model. The results of analysis suggested prevalence of income inequality. Crop produc- tion was the main source of income in the agroforestry systems of the study area. Earnings from crops and timber were decreasing income-inequality amongst smallholder farmers. Our disaggregated analysis showed that off- farm income was also decreasing income-inequality for farmers with farm- lands located close to homestead, for female-headed households, for farmers who did not access extension services, and those who were members of com- munity-based financial institutions. Estimated incomes increased with house- hold assets, size of farmland, and age of household head. However, the same decreased with household size. We found gender disparity to be one of the key issues that need attention in formulating future policies to reduce ine- quality. We recommend promotion of livelihood diversification as well as the designing and implementation of tailor-made training and farm financing mechanism to help the less resource-endowed farmers in mountain areas to raise their economic portfolios and social status and combat income poverty and inequality.