Market participation by smallholder farmers has the potential to pull farmers out of poverty while at the same time increasing food security at the more aggregate level. This paper looks at the dynamics of smallholder maize and beans marketing in Uganda and Mozambique. Using panel data from both countries, we categorize households according to their gross sales position over multiple periods of time and differentiate the occasional seller from the persistent seller. We describe patterns in the dynamics of smallholder commodity marketing and explore correlations with factors identified in previous theoretical and empirical work that are assumed to affect market participation. We also estimate multinomial random-effects models and compare the results of such an analysis of the dynamics of smallholder marketing with a static analysis.