Increased awareness among coffee consumers of the impact of their consumption habits on the people and environment in coffee producing countries has resulted to implementation of certification programs in the coffee sector as an assurance of good practices in production and marketing of coffee. The UTZ certificate was the first to be introduced in the Kenyan coffee industry and this study provides the first quantitative assessment of its impact on smallholder farmers. The propensity score matching technique was used because it solves the ‘selection bias’ problem in assessment of the impact of development programs. The impact of the certification program differed between the two regions where it is being implemented probably due to the differences in bio-economic characteristics. Overall, the impact of the program ranges from higher coffee prices and coffee incomes, increased access to greater amounts of credit for agricultural purposes, increased incomes from other crop enterprises or off-farm activities, greater savings by households and increased investments on land. UTZ certification also resulted to better service provision by the cooperative societies. The perception by certified households that their economic situation has not changed may be attributed to the short period that the certification program has been in existence and also to the reference period (2008) which was a difficult year in Kenya due to the post election and economic crises.