The main objective of this study is to investigate the use of social networking sites (SNSs) for marketing of academic library services. Specifically the objectives are to: explore the use of SNSs by academic libraries, investigate the perceptions of academic librarians towards marketing of library services through SNSs, and determine the predictors that may influence users' engagement in the electronic word-of-mouth (eWOM) via SNSs. This study employs the qualitative and quantitative approach. It is conducted sequentially in three phases. First, the priority is to explore the social networking sites (SNSs) used by the academic libraries in Malaysia by means of web analysis of academic library websites and library SNSs pages. The second phase involves structured interviews to investigate the perceptions of academic librarians on the use of SNSs for marketing of academic library services. Finally, the third phase focuses on quantitative method through a survey to determine the predictors that influence user's engagement in electronic word-of-mouth (eWOM) through SNSs.