Cassava (Manihot esculenta crantz) is a crop of global significance especially in the tropics where it is a source of food, animal feeds and industrial starch. However, the rapid Post- Harvest Physiological Deterioration (PPD), bulkiness of fresh cassava roots and high toxicity of some cassava varieties prohibits prolonged marketing and market participation of smallholder farmers. A cross-sectional study was conducted in north and north-eastern Uganda to ascertain the drivers of market participation for smallholder cassava farmers. Data were collected using pre-tested questionnaires administered to 185 randomly selected respondents and using STATA package, a two stage Heckman’s model was fitted involving a Probit model and OLS regression in the first and second stages, respectively. Results of the first stage Probit model revealed that farm land size, market distance, size of household, transport cost and off-farm annual income significantly (P<0.05) influenced the market participation decisions of smallholder cassava processors. In the OLS regression of the outcomes model, gender, market distance, contract marketing, marketing experience, education level, and land allocated to cassava production and group marketing significantly increased the sales revenues of processed cassava products. Our findings indicate that socio-economic and institutional factors are important in stimulating smallholder cassava farmers’ market participation. Therefore, policy support is needed in the areas of contract marketing, processing to prolong cassava shelf-life, strengthen market access conditions and lift smallholder farmers from income poverty.