The book collects the lectures delivered during the 7th International Summer School on Atmospheric and Oceanic Sciences (ISSAOS) titled “Integrated Ground-Based Observing Systems Applications for Climate, Meteorology, and Civil Protection”. The book aims to contribute to the scientific understanding of basic concepts and applications of integrated ground-based observing systems. The first part describes most common instrumentations with their strength and limitations; strategic plans for the deployment of an observation site are discussed, together with an overview of techniques for integrating heterogeneous data. The second part introduces cutting-edge applications, including assimilation in numerical weather prediction, climate benchmarking, air quality monitoring, and meteo/hydrological warnings.