Cross-functional virtual work teams had been around for decades. However, there was limited understanding about how learning process toke place in the cross­-functional virtual teams (Robey et al., 2000). The separation of team members in dispersed physical locations made the social learning process difficult (Wilson, 2003). The question of what kind of factors would affect the performance of the team related to learning is significant for both researchers and companies. As cross-functional virtual work team applications continue to grow and it required the skills and knowledge of a whole range of people, knowledge sharing and trust building should be crucial for the team (Alexander, 2000; Jarvenpaa, 1998). The main objective of this thesis was to investigate the ways that members of cross- functional virtual teams were engaged in the knowledge sharing and the development of interpersonal trust as well as the leadership influence (Kerber & Buono, 2004) by identifying the benefits and analyzing the mechanisms that might help to manage such kind of teams as well. To investigate all those issues, in-depth interviews with participants including managers, top management and some specialists in the cross-functional virtual team had been conducted in a local telecom company and also two of its vendors. The virtual teams bridged not only functional divides but also geographic and cultural ones, and members used a variety of media to manage the production and delivery of products and services to serve their customers. The final results of this study revealed the following findings, which would help solve the relevant research questions: • The reasons and benefits for knowledge sharing and trust building in the cross­-functional virtual team; • Different mechanisms could be developed amongst the virtual teammates in order to facilitate knowledge sharing and trust building in the cross-functional virtual team; • The roles and responsibilities of a leader in the cross-functional virtual team had been identified; • The relationship among knowledge sharing, trust building and leadership in the cross-functional functional virtual team had been developed.