Purpose - The purpose of this research is to develop a Social Information System research model that uses the core constructs intrinsic motivation, extrinsic motivation, and amotivation to explain social networking adoption among tweens, teens and young adults. Methodology - In developing the research model, we triangulated theories to examine the different orientations of motivation. The data collection process included a stratified sample size of 270 respondents. Following data collection we analyzed the results using structural equation modeling in the Partial Least Square software package. Findings - The constructs amotivation, intrinsic and extrinsic motivations were all statistically significant in explaining continuance intention to use social networking services (SNS). Practical implications - Researchers and practitioners have intimated that although there has been a rise in the number of persons accessing and becoming members of SNS, several subscribers who join subsequently leave after a minimal period. The practical implication of this study lies in providing a preliminary understanding of what determines or inhibits continuance intention of SNS membership. Originality/value - Despite efforts, research in IS and technology acceptance literature regarding SNS diffusion is limited in scope. The theoretical implication of this study lies in the model that has been developed and validated to provide a more effective tool for the scholarly evaluation of SNS adoption. Existing adoption models are insufficient to explain voluntary technology usage of this nature. © 2013 by Emerald Group Publishing Limited.