The purpose of the present study is to explore the role of behavioral/psychological constructs of passion and self-determination in the context of social networking site (SNS) addiction. The present study explored SNS addiction by employing a dualistic framework, which is an amalgam of the dualistic model of passion ([13]) and the self-determination theory (SDT; [14]). Data were collected through an online survey administered by a market research company based in the USA (N = 312). The survey consisted of items related to key constructs related to the research framework proposed (e.g., harmonious and obsessive passion). All the items included in the survey were 7-point Likerttype questions. Additionally, data related to demographics and Internet usage were collected. Structural equation modeling (SEM) was employed to explore the relationships between passion typologies, self-determination, and SNS addiction. Structural Equation Modeling showed that harmonious passion was positively related to autonomy and relatedness, but was negatively related to competence. Obsessive passion was negatively related to autonomy, competence, and relatedness. Competence and relatedness were negatively related to SNS addiction. Obsessive passion positively influenced SNS addiction, whereas, contrary to the expectation, harmonious passion also positively influenced SNS addiction. Obsessive passion towards SNS predicted SNS addiction via three basic psychological needs, namely, autonomy, competence, and relatedness. The present study draws upon concepts of positive psychology to understand SNS addiction. The proposed theoretical framework explained 86% of the variance in terminal construct, which is SNS addiction.