Smallholder farms in the humid highlands of East Africa are undergoing changes that question the notion of the rural space. Characterized by land degradation, increasing population pressure, intensive farming and continuous cropping in small plots, smallholder farmers have increasingly embraced additional forms of nonfarm income generation activities. The observed changes put to question parameters used in the analysis of smallholder farming systems in the region. In this paper, we endeavour to analyze how these changes in smallholder farming systems influence investments of proven sustainable land management practices. The paper is based on a study of 320 farm households comprising 494 plots in the western Kenya region. For cross-section data, use is made of the OLS and instrumental variable methods to explain investments in sustainable land management. In contrast to a number of recent studies, specification is made of non-farm income (NonFarmincome) as income from non-agricultural activities, and natural resource-based income (NRMincome) as income from natural resource management activities undertaken away from individual farm holdings. The NRMincome activities have an implication on landscape conservation, as they are mainly undertaken in communal and other public lands. Results show that non-farm income contributes to investments in soil prevention practices, contrary to the results of a number of studies looking broadly at off-farm incomes. The findings have implications for suitable policies for enhancing sustainable land management. This study argues that those policies need to focus on landscape level conservation, enhance non-farm income, and address impacts on communal lands and other common property regimes resulting from smallholder farmers’ natural resource management income strategies.