This is a research graduation project for the master program Science Communication program at TU Delft, conducted at TNO as a research internship: ‘Social Networks as a Driver of Sustainability Behavior’, from January 3rd to July 1st, in 2011. With the rise of social media, collective actions in the forms of social movements and campaigns regarding sustainable issues are attracting more attention and online participation. This results in ‘online slacktivism’, which refers to the phenomenon where a large population participate via the internet. However, it is not clear yet which factors in social media communication strategies contribute to ‘online slacktivism’, nor the impacts and implications of such phenomenon on relevant stakeholders and issues. To understand the extent to which social media communication factors contribute to the participation of online slacktivists in energy campaigns, this study is designed with a triangulation of qualitative and quantitative methodologies. In the qualitative case study, literature survey, semi-structured interviews, observations and cluster method are applied to investigate the social media communication strategies applied and to identify the social media communication factors. In the quantitative analysis, 55 energy campaigns are analyzed based on the conceptual framework established from the qualitative study. By operationalizing the concepts and applying factors analysis to reconstruct the conceptual framework, multiple regression analysis is conducted to investigate the relationships between the social media communication factors and the participation of ‘online slacktivist’ in energy campaigns. It is observed that there are differences in the conceptual frameworks in the qualitative case study and the quantitative analysis. It could be concluded from the multiple regression analysis that: i) factors with lower perceive ease of use, more effort to perform actions and behavior objectives which has higher relevance to real-world actions in the concept ‘action barrier’ has a negative effect on participation ii)factors with presence of interaction through discussion, presence of online community, the possibility to collaborate, and share in the concept ‘network opportunities’ contribute positively to participation iii) factors with rational arguments and presence of use suggestion/tips in the concept ‘content of the communication message’ contribute negatively to participation iv)factors with presence of visualization of group achievements, competition, individual and group achievements, and personal profile in the concept ‘comparison of social content’ contributes negatively to participation. For factors which are excluded in the regression analysis, future research need to be carried out to investigate the extent of their contributions to participation. The report ends with discussions on the research results, quality of the research, implications for relevant stakeholders and issues, and also gives recommendations for future study.