This paper explored how social media characteristics affected users’ attitudes toward the utilization of Greater Amman Municipality (GAM) e-project management located in Jordan. Data were collected through online survey, involving 456 GAM e users, and analyzed using partial least squares-structural equation modelling. Results showed user attitudes and social media characteristics (reliability, security and website design) as direct significant antecedents of GAM e-project management usage. Furthermore, three direct significant relationships were shown between social media characteristics and GAM e-project management usage. Results also demonstrated three direct significant relationships between social media characteristics and users’ attitudes. Next, results showed one direct significant relationship between users’ attitudes and GAM e-project management usage. Three indirect significant relationships between social media characteristics and GAM e-project management usage were detected via mediation of users’ attitudes. This study recommended (among others) paying attention to other social media characteristics that have impact on GAM e-project management usage, namely, responsiveness, privacy, and site content.