 The International Soil Moisture Network, ISMN, is a centralized data hosting facility that collects and makes available globally available in situ soil moisture measurements from operational networks and validation campaigns. Data collecting networks share their soil moisture datasets with the ISMN on a voluntary and no cost basis. The database contains data of 19 networks and more than 500 stations located in North America, Europe, Asia and Australia. It spans from 1952 until the present, although most datasets have originated during the last decade. The ISMN is rapidly expanding and will become an increasingly important resource for validating an improving satellite-derived soil moisture products and studying climate-related trends. Potential networks are invited to enrich the collection by sharing their in situ soil moisture data.