The transition to sustainable agriculture in tropical small-scale farming has been discussed intensively since Boserup published her theory on the role of population pressure as a leading factor. Bosemp's work challenged the Malthusian approach to rural transformation. Recent evidence supports the Boserup theory as applied to Machakos District, Kenya. This paper aims to establish how much of terracing is directly explained by population density increases as opposed to other district and village-level variables by using a retrospective multivariate analysis in Machakos and Kitui Districts, Kenya. The findings suggest that variables such as the distance to major urban markets and the windfall profits from the coffee boom in the late 1970s are at least as important in explaining the investment in the quality of land in Machakos and Kitui Districts. © 2002 Elsevier Science Ltd. All rights reserved.