A large-scale online survey (n=1327) was utilized to investigate determinants of perceived usefulness and perceived ease of use as well as other effects on the formation of a behavioral intention to use social network sites (SNS). Findings show that need-based motivations such as social deficit, communication need, and community need do positively impact perceived usefulness while hedonic need and contribution need do not. Additionally, perceived ease of use was affected by technologyoriented self-efficacy. Trust and privacy considerations impacted perceived usefulness as well, while external threats to security did not. Finally, age and gender effects on the underlying technology acceptance model constructs were also explored.