Many contemporary climate change and food security initiatives, including climatesmart agriculture (CSA), call for connecting and integrating different government levels, policy domains, and organizations. This boundary-crossing is frequently accompanied by difficulties including turf wars and power struggles, which risk to thwart policy development. Although the literature argues that policy entrepreneurship contributes to the crossing of level, domain, and organizational boundaries, knowledge on these dynamics is fragmented, and insights into entrepreneurial strategies, embedded in the policymaking context, are limited. Consequently, the aim of this dissertation is to understand how policy entrepreneurship contributes to the crossing of boundaries to achieve CSA. The aim is addressed through three research questions: (i) how and why do policy entrepreneurs cross boundaries for climate-smart agriculture; (ii) how does the policymaking context influence cross-boundary policy entrepreneurship for climate-smart agriculture; and (iii) how can cross-boundary policy entrepreneurship in the policy process for climate-smart agriculture be conceptualized?To understand policy entrepreneurship's contribution to the crossing of boundaries, the dissertation focuses on two case studies of CSA policy development: the Global Alliance for Climate-Smart Agriculture, and the National Climate-Smart Agriculture Strategy in Kenya. These cases have been studied through a mixed-methods research design, including a systematic literature review, congruence analysis, and frame analysis.