The purpose of this study is to examine the variables that predict social media addiction. The following hypotheses have been tested for this purpose: Hypothesis 1: The level of social media addiction related to the weekly time spent on social media. Hypothesis 2: Narcissism, happiness, and weekly time spent on social media predict social media addiction at statistically significant levels. This research is a descriptive study in the relational screening model. Participants in this study were selected using the convenient sampling method. A total of 239 adults (140 females: 58.6 %; 99 males: 41.4 %) living in different parts of Turkey were included in the study group. Data were collected by Social Media Addiction Scale, Happiness Scale – Short Form, Narcissistic Admiration and Rivalry Scale and Personal Information Form in this study. The data collection process was completed between November – December 2017. In the analysis of the data, the frequency, percentage, independent sample t-test, Pearson correlation coefficient, and stepwise regression analysis were used. As a result of this research, it was found that social media addiction differed significantly compared to the average weekly time spent on social media. Besides, narcissism, average weekly time spent on social media, and happiness variables were found to predict social media addiction significantly. According to this result, narcissism and the average time spent on social media predicts social media addiction in a positive way and happiness in a negative way. Finally, these results were discussed according to the literature and suggestions were given for future studies.