Minimum tillage (MT) is a key component in the promotion of conservation agriculture (CA). This paper asks whether MT reduces cropland expansion and thus deforestation. We develop a simple theoretical household model of land expansion, and test hypotheses by estimating a double hurdle model using household survey data from 368 smallholders in rural Zambia. We find that about 19% of the farmers expanded cropland into forests, clearing an average of 0.14 ha over one year. Overall, MT adoption does not significantly reduce deforestation among households in our sample, while labor availability stimulate expansion. Yield augmenting agricultural technologies (such as MT) may not reduce expansion unless combined with other forest conservation measures.