The Toolkit for Ecosystem Service Site-based Assessment (TESSA) has been developed through a collaboration of six institutions with input generously provided by scientists and practitioners from multiple disciplines. The toolkit provides accessible guidance on low-cost methods for how to evaluate the benefits people receive from nature at particular sites in order to generate information that can be used to influence decision making. This toolkit is designed to overcome this obstacle by providing practical guidance on how to identify which services may be significant at a site of interest, what data are needed to measure them, what methods or sources can be used to obtain the data and how to communicate the results. The toolkit emphasizes the importance of comparing estimates for alternative states of a site (for example, before and after conversion to agriculture) so that decision-makers can assess the net consequences of such a change, and hence the benefits for human well-being that may be lost through the change or gained by conservation. The toolkit has attempted to find a balance between simplicity and utility of developing convincing information for decision-makers and therefore excludes consideration of some of the more advanced concepts in ecosystem services. This is so that it can be used by non-experts, yet still provide scientifically robust information. TESSA is primarily aimed at conservation practitioners, although the methods may be applicable to a wide range of users, including natural resource managers (e.g. forestry, fisheries, water managers), land-use planners, development organisations (e.g. for poverty alleviation), and the private sector.