Like many other Sub-Sahara African countries, the contribution made by smallholder farmers in Tanzania’s economy cannot be under estimated given the fact that, majority depend on them for food security and industrialization process. Unfortunately, most of these farmers are not performing well, hence having little contribution to the economic development of the country and eventually to their socioeconomic wellbeing. Socio-economic determinants have been associated with limiting these farmers to achieve their fully market participation potentials. This study therefore used binary logistic regression model to iron-out socio-economic determinants of smallholder farmers’ market participation, taking a case of smallholder maize producers in Kongwa and Mpwapwa Districts in Dodoma Region. The aim of this study is to provide the insight for improving market participation, not only to smallholder maize farmers but also other crops farmers in the whole country. The study empirically found that, education level, household size, social capital, farm size, type of transportation facility, roads condition, and market guarantee were positively influencing farmers’ choices to sell maize. While, higher ages, sex and market distance were negatively influencing their choice to participate in the market. The study concluded that, in order to increase market participation of smallholder maize farmers, the following has to be done; improving farmers level of education, at least at primary level, as it improves ability of farmers to grasp various agricultural technologies; encouraging gender balance and social networks in rural areas; emphasizing on market guarantee such as contract farming; improving rural infrastructures as well as creating more market places closer to villages and rural areas.