The mango subsector is a major source of income for farmers in Kenya. However, due to marketing imperfections, smallholder mango farmers do may not be receiving a fair return on their income. This study examined the effect of collective marketing on mango income for 226 smallholder farmers in Mwala sub-county. The study employed an endogenous switching regression model to account for selection bias from observed and unobserved farmer attributes. The results reveal that participation in collective marketing significantly boosts mango income.