The new social medium Twitter provides a unique opportunity for agenda setting scholars as a new source of public opinion. This thesis argued that this new measurement could be used as an indirect measurement of public salience. Twitter stores information posted by users of its service in a searchable and quantifiable mode. Freeing information that was private on other social networking sites, such as Facebook, issues can be tracked on Twitter much like that of a news archive, such as Google News or The Vanderbilt Television News Archive. Three popular public issues were tracked for a total of 92 days. The issues chosen were Immigration, BP Oil and the Mortgage and Housing Crisis. First and second-level agenda-setting variables were coded for national television newscasts and newspapers. These variables were interpreted as measurements of media salience and assigned as independent variables. In addition, Tweets were tracked and labeled as public salience. They were inversely named as dependent variables. Correlations were assessed, and a time series analysis was conducted to determine whether the independent variables were sufficient predictors of the dependent variables. Alternative explanations and conjecture not withstanding, this thesis found a mild relationship between media salience and public salience as it defined it. For the issues of BP Oil and the Mortgage and Housing Crisis, two independent variables were predictors of the dependent variables. For the issue of Immigration, only one independent variable was a predictor. The lack of predictors for the Immigration issue was attributed to an error between dependent and independent variables. Media salience was determined to consist of national news stories while public salience was determined to contain global stories. For all cases, the agenda-setting effect occurred on the same day. Ultimately, this thesis was an extension of agenda setting into a new digital medium. The mild support found echoes the agenda-setting research of the past that states traditional mass media outlets affect and set the agenda of the publics that listen to them.