This study employs the endogenous switching regression model to examine the impact of the adoption of recommended tea plucking interval on tea yields among small-scale tea farmers in main tea-growing regions of Kenya. The study utilises cross-sectional farm household level data collected from a randomly selected sample of 413 households. Results support the notion that self-selection occurs and that estimates that do not consider selection-bias would be biased. Different determinants are found to be significant in explaining the tea yields for adopters and non-adopters. Thus, policy makers should consider these differing effects when designing development projects to increase tea yields.