Book excerpt: Extension and advisory services (EAS) play a key role in facilitating innovation processes, empowering marginalized groups through capacity development, and linking farmers with markets. Advisory services are increasingly provided by a range of actors and funded from diverse sources. With the broadened scope of EAS and the growing complexity of the system, the quantitative performance indicators used in the past (e.g. related to investment, staffing or productivity) are not adequate anymore to understand whether the system is well-functioning. To enable evidence based and informed policy and investment decision for extension and advisory systems, the EAS-Yardstick (EAS-Y) has been developed through a consultative expert process. It constitutes a holistic scoring tool based on a comprehensive set of metrics that can capture all the nuances of the pluralistic EAS. Metrics are organized into two modules, related to EAS performance and to EAS outcomes, each subdivided into key EAS topics. These cover elements of the EAS enabling environment, scope and provision of services, and coordination, collaboration and learning in the system. At the outcome level, topics include the acquisition of skills, changes in behaviours and livelihood transformations. All metrics are operationalized through a scoring mechanism. EAS-Y is digitally enabled through the Kobo toolbox and is used for participatory assessments in various contexts. Assessments can support a systematic crosscountry analysis, complementing findings from more specific impact evaluations of EAS interventions or in-depth process evaluations. As such, it contributes to substantially enhance EAS system performance and outcomes by guiding investment and policy decisions.