This study investigates the impact of package adoption of inorganic fertilizers and improved maize varieties on yield among smallholder households in Kenya. We used a blend of the quasi-experimental difference-in-differences approach and propensity score matching to control for both time-variant and time-invariant unobservable household heterogeneity. Our findings show that inorganic fertilizers and improved maize varieties significantly improve yields when adopted as a package rather than as individual elements. The impact is greater at the lower end of the yield distribution than at the upper end, and when technical efficiency of the farmers improves. A positive effect of partial adoption is experienced only in the lower quantile of the yield distribution. The policy implication is that complementary agricultural technologies should be promoted as a package, and should target households and areas which are already experiencing low yields.