While the majority of libraries now have a social media presence, few have assessment strategies in place to measure the overall effectiveness of their social media activities. Over the past year, we have gathered activity, audience and engagement metrics on social media usage by public and academic libraries across Canada. In this presentation, we will provide a detailed analysis of various social media accounts, highlighting what makes the most popular accounts effective at connecting and engaging with members of their communities. Although we will emphasize the social media accounts of libraries in Eastern Canada, we will also discuss social media usage by larger institutions such as the Toronto Public Library and the University of British Columbia Libraries to compare and contrast the assessment strategies they use. Recommendations will be given on how libraries in Eastern Canada can best manage their social media presence, and how the effectiveness of social media activity can be assessed and improved.