The purpose of this study is to understand how social responsibility perceptions of a brand influence Millennial consumer's brand interaction on Social media. We specifically look at Instagram as it is the most used form of social media by Millennials today. We further investigate the effect of Instagram engagement on perceived brand accessibility and purchase intention towards the brand. This paper analyzes primary data collected from Millennials through online surveys in the United States. Structural equation modelling is used to analyze data and empirical evidence supports the proposed model. Results indicate that Millennials perceive higher value for brands who are socially responsible. They actively pursue such brand online and interact with those. Increased involvement in brand and its efforts through Instagram engagement further enhances intentions to purchase the brand.