Water Harvesting (WH) represents one of the most important strategies for coping with water shortage in arid and semi-arid regions, where water scarcity has physical and meteorological causes, and where political, social and economic reasons may hamper a safe access to water. In drought prone farmlands, WH represents a fundamental source of water for sustaining agricultural production and increase productivity (Rockstrom et al., 2002; Motsi et al., 2004; Okhravi et al., 2015; Zahraei et al., 2017). It can represent also a viable option to restore degraded agro-ecosystems, that can both provide renovated ecosystem services to farmers and produce animal fodder in restored grazing lands (Castelli et al., 2017; Oweis, 2017). In order to fully develop the potential of implementing WH to support farming (and agro-pastoral) systems in drought-prone areas of the world, researchers, professionals and practitioners should develop a complete knowledge of all the possibilities connected to these techniques. WH is also often rooted in the historical knowledge of rural populations, and, sometimes, these traditional, site-specific, techniques need only to be rediscovered and inserted in water management strategies. To do so, this chapter firstly explores the definitions of WH, identifying four main sub-categories (Section 2). The fundamental structure of a WH system and the physical and management strategies are then presented. Section 3 presents the main features of Floodwater Harvesting (FWH) and, with a case study example from Ethiopia, discuss the importance to involve local communities in designing and managing the system. Section 4 discusses Macro catchment Water Harvesting systems (MWH), and, with a case study in Kenya, presents an example of planning multiple sand dams combining GIS approach and indigenous knowledge. Section 5 analyses micro catchment Water Harvesting (mWH), presenting a case study from Ethiopian Highlands where mWH triggered upstream-downstream issues connected with water allocation. Section 6 presents the main applications of Rooftop Water Harvesting (RWH) in farmlands, and, with an example from rural Guatemala, explains the need for a regular monitoring and maintenance of WH infrastructure. In Section 7, the reasons for integrating soil fertilization with WH are explained and discussed. Section 8 reports a short resume of the main features regarding planning, designing, managing and maintaining WH systems in farmlands, discussing upstream-downstream issue that may occur at watershed scale, including also the diverse strategies that can be taken in consideration for FWH, MWH, mWH and RWH. Future developments are also presented. While not representing a review, the study drafts on multiple experiences carried out around the globe about water harvesting in farmlands. While adopting the most common definition for WH, it should be acknowledged that other definition and subdivision of WH techniques can be found in the literature.