Tourism is a cornerstone of Spain's economy and a key driver of regional development. This report presents indicators to monitor tourism sustainability in Andalusia, Catalonia, Navarra, and the Region of Valencia, building on existing frameworks and good practices at international, national and regional level. A set of 30 indicators and 57 metrics is informed by key policy issues and priorities identified in existing tourism strategies and measurement frameworks in the four regions. They cover economic benefits, seasonality, local resident perceptions, accessibility, climate change mitigation and water management. A sub-set of ten 'priority' metrics has also been identified to monitor key policy issues and help prioritise action towards sustainable development. The report highlights avenues for future development to refine indicator methodologies and close existing data gaps on central policy issues such as cultural heritage, greenhouse gas emissions, waste and digitalisation.