Research on decision-making processes and the diffusion of innovations in organizations has been focused on the influence of formal organizational structures. Since the successful implementation of most innovations requires the cooperation of employees, it is important to investigate how employees' knowledge, opinions, and individual decisions concerning an innovation are influenced by other employees. The present study investigates how information acquisition and adoption decisions of employees are influenced by the quantity and strength of their informal communication ties in the organization, and how strong this influence is in comparison with influence from formal communication sources. Results indicate that formal communication sources contributed more to the process of information diffusion, whereas informal communication sources (especially the employees' strong ties), were more influential on attitudes and adoption intentions.