This study aimed at evaluating the link between tourism development, well-being and residents’ access to livelihood capitals when confounding variables are controlled. The study used the quasi-experimental design. Well-being condition was determined through the Livelihood Capital Index after controlling for socio-economic covariates among matched samples of 413 tourism beneficiaries and 421 non-beneficiary agro-pastoralists living in three gateway tourism destination communities namely Burunge, Lake Natron and Loliondo in Northern Tanzania. Selected communities experienced a development stage of tourism destination life cycle. This study largely relied on analysis of quantitative data by calculating the Livelihood Capital Index. However, qualitative data from 24 key informants, through Focus Group Discussions complemented the quantitative data. The study established that linkage between tourism development and well-being is facilitated with residents’ access to livelihood capitals. Basing on difference in the average treatment effect of 0.087 (8.7%) in the livelihood capital index, which was statistically significant (p <0.001), the study concluded that residents’ well-being as a function of livelihood capital status is enhanced more with tourism than without tourism, especially in financial, social, physical and human capitals. Therefore, the study recommended that efforts to sustain tourism development in enabling resident access to livelihood capitals that underpin their well-being should strike a balance between residents’ need for cultivation and grazing at one hand and tourism investment on communal land on the other hand.