Introduction: In Rio de Janeiro State floods are a frequent phenomenon. The main causes are climate change, environmental degradation, population growth, urbanization processes, and social inequalities. However, some places/groups are more vulnerable, less able to absorb the impacts, or to adapt and adjust themselves to such events. Vulnerability can be defined as the susceptibility of social groups to the potential effects caused by dangerous events or the resistance and resilience of society to dangers. Considering that the risk is not equally distributed and floods occurrences and damages have been increasing, the evaluation of vulnerability has been considered a key tool to risk reduction and community resilience. Methods: Following the methodology applied by Flood Hazard Research Centre (FHRC), social vulnerability to floods in the Rio de Janeiro State was measured using a Social Flood Vulnerability Index (SFVI). In developing countries, social vulnerability is associated with poverty and social inequalities. So, the SFVI was built using social indicators that indicate social disadvantage for each of 92 municipalities of Rio de Janeiro State gathered from Census data. The indicators were then transformed in Z-scores using Excel 17. The sum of the Z-score generates the SFVI of each municipality. SFVI was mapped. Results: Thirty-six (around 39%) of the 92 municipalities of Rio de Janeiro State are classified as very high social vulnerability to floods. Twenty-one (23%) are classified as high social vulnerability to floods. Twenty-five (27%) are classified among medium, low and very low social vulnerability to floods. Conclusion: Fifty-seven municipalities of Rio de Janeiro State (62%) have very high or high social vulnerability to floods events. This information is important to promote public actions to decrease the vulnerability, improve the resilience and reduce floods risk in the area.