Improved varieties are considered critical for increasing crop yields worldwide. This study explored the effects of public agricultural extension and pest and disease experience on adoption of improved varieties using survey data on 525 wheat farmers in Anhui Province, China, to which the Heckman sample selection model was applied. The results showed that public agricultural extension had a significant positive relationship with adoption of improved varieties. Demonstration and training, as different forms of agricultural extension, both increased the probability of farmers adopting improved varieties, but only demonstration had a marked effect on degree of adoption. Pest and disease experience increased the probability of adoption of improved varieties by farmers and significantly enhanced the effect of public agri-cultural extension, but did not affect degree of adoption. Further analysis using an endogenous switching regression model revealed that adoption of improved varieties raised wheat yields by around 337.83 kg/ha. Public agricultural extension should thus be strengthened, especially for farmers with pest and disease experience, and a diversified, well-functioning agri-cultural extension system should be provided.