A number of questions remain to be addressed concerning the stability of Social Network Services (SNS) as members join and leave. The question of what factors contribute to user behavioral intentions toward SNS is important. A comprehensive model is proposed based on a broadening and deepening of Theory of Reasoned Action (TRA) to explain SNS users’ behavioral intentions. The propositions presented seek to provide answers to the following research question: What are the effects of intrinsic/extrinsic motivations and social influences on users’ behavioral intentions toward SNS based on TRA, Technology Acceptance Model (TAM) and flow theory? Simply put, this study investigates the interrelationships between perceived usefulness, perceived ease of use, flow experiences, social influences, attitude and behavioral intentions within SNS contexts.