Corporate Social Responsibility (CSR) is increasingly more important for firms in today's global marketplace and effective communication of CSR initiatives is vital towards enhancing a company's reputation and its sales revenues. With this consideration, the reputations of firms in the Aerospace and Defense (A & D) industry worldwide, in conjunction with their use of social media were examined to validate a link between the use of social media to communicate CSR activities and a firm's reputation ranking. The methodology involved a qualitative content analysis of the online and social media presence of the top 20 A & D companies from the Deloitte Toche Tohmatso Limited (DTTL) 2014 Global A& D financial performance study. Data from six indicators of CSR: environment, community relations, diversity, employee relations, human rights, and client comments, was examined. According to the findings, firms utilizing social media for CSR communication should expect improved reputation ratings. All top 20 A & D companies publish at least four CSR indicators on social media platforms. The conclusion reached is that, while CSR content via social media can lead to higher reputation ratings, companies need to strategically choose the ideal number of CSR indicators, to position themselves in the global marketplace.