The development of Vulnerability Assessments (VA) to climate change is a rapidly evolving activity within the broader climate adaptation planning process. As such it is receiving significant attention from the communities of adaptation researchers and practitioners. It is uncommon to carry out more than one VA in the same place and at the same time thus this case study presents a unique opportunity to compare the application of three different Vulnerability Assessment approaches that were carried out simultaneously in the same location: the Nor Yauyos Cochas Landscape Reserve in Peru, during the period of 2012 through 2013. All three approaches shared the goal of identifying Ecosystem-based Adaptation (EbA) measures based on the ecological and social vulnerabilities the VAs helped to identify in the target area. Each approach, however, was different in terms of methodologies and conceptual foundation. The following case study describes the application of a participatory VA approach, a model-based VA approach, and a deductive VA approach, using a set of descriptors in a custom-designed matrix. We also present a narrative description of each approach to explaining in more detail the process undertaken by each Vulnerability Assessment. Key lessons learned are that EbA measures require abundant information (pertaining to climate, ecosystems, biodiversity, land-use practices, livelihoods, etc). As a result, the interaction between scientific knowledge and traditional (local) knowledge is vital. Of importance, all three approaches rendered useful and pertinent results and surprisingly recommended very similar adaptation measures. Nevertheless, the participatory approach was the only one that did not require additional studies to implement measures following the Vulnerability Assessment. The three approaches also proved to be advantageous for application at different scales. While the participatory approach turned out to be most useful at the community level, the model-based approach and the deductive approach delivered information at a broader scope that served to better understand vulnerability for the entire ecosystem target area.