Building on past research on trust and social presence, this study explores how multimedia vividness and social presence affect trusting beliefs and subsequently trusting intentions of a computer-based decision aid. An experiment involving 550 subjects examines the effect that decision aid personality and increased levels of vividness (text, voice, and animation) have on social presence, and downstream trust-related constructs including trusting beliefs and trusting intentions. The effect of a user’s computer playfulness on social presence is also investigated. Past research on trust and social presence provide the theoretical foundation for the study and suggest that increased vividness may moderate the effect of decision aid personality on perceptions of social presence, with social presence consequently affecting trusting beliefs.