The aim of this dissertation was to study the little examined, yet important issue of leadership for distributed teams. Distributed teams are defined as: “teams of which members are geographically distributed and are therefore working predominantly via mediated communication means on an interdependent task and in realizing a joint goal” (adapted from Bell & Kozlowski, 2002 and Dubé & Paré, 2004). Chapter 1 first presents the outline of the dissertation. Next, several characteristics of distributed teams are discussed. These characteristics render team processes more difficult. Because theory on management and leadership is based mostly on research in conventional (co-located) organizations there is a need to address leadership in distributed teams. The dissertation aims do this by answering the question: “What is effective leadership for distributed teams?” In chapter 1, several developments, which have lead to the increased use of distributed teams in organizations are discussed. One of these developments is considered an enabler (ICT developments), while others are considered drivers (e.g. globalisation, cost reduction, business continuity, flexibility and using networks of expertise). In the discussion of these developments, some examples of distributed teams that have emerged in organizations are presented. In the second part of Chapter 1, a body of literature on leadership for distributed teams is reviewed. First, based on practitioner oriented sources, some tasks, roles and responsibilities of leaders of distributed teams are discussed. This is followed by a review of findings of empirical studied aimed at leadership in distributed teams. The chapter concludes that empirical research aimed at leadership in distributed teams has been scarce, particularly when it comes to field studies. It also concludes that transformational leadership seems promising for distributed teams, as it is associated with favourable team outcomes. Findings from the normative literature and explorative studies have not been integrated in quantitative field studies. For field studies of leadership in distributed teams a hybrid approach, which combines existing leadership theory with new leadership concepts, while incorporating team context systematically, is proposed. In Chapter 2, findings of an explorative study (study 1) are reported. The main purpose of study 1 was to investigate the challenges associated with characteristics of distributed teams, as well as leadership actions and behaviours to overcome these challenges. Four questions were posed at the beginning of this study: 1. “How do leaders from distributed teams in organizations perceive the impact of geographic distribution, mediated communication, time dispersion and cultural differences on distributed team work?” 2. “What are the most important challenges with distributed team work, as perceived by distributed team leaders?” 3. “What, according to leaders, are effective leader behaviors to overcome these challenges?” 4. “What can we learn from this first study in terms of promising areas for research?” For this study a series of semi-structured interviews (n=50) with team leaders of distributed teams from nine different multinational organizations was held. Before the interviews, information about the team’s tasks and management structures was gathered by means of a short on-line questionnaire (see Appendix II). For the purpose of these interviews a general interview script was designed (see Appendix III). Leaders were asked how they experienced characteristics of their distributed teams as influencing their team and their role as leaders. All interviews were recorded, transcribed and then analyzed with a program that supports analysis of unstructured data (Atlasti). In this process a codebook was generated (see appendix IV). The second part of Chapter 2 presents several types of distributed teams, as well as the results of the study in the following order: geographic distribution, mediated communication, time differences and cultural diversity. Respondents indicated that geographic distance lead to complex team structures and the emergence of sub-teams. Mediated communication leads to a lack of visual cues, a lack of awareness and a lack of informal encounters. Few problems were reported as a result of time differences, although the planning of meetings was sometimes difficult. Cultural diversity was mentioned to lead to differences in communication styles, to language problems and to differences in hierarchy perception. From the results of study 1, two major challenges emerged (1) development of effective working relationships and (2) development of shared understanding. The third part of Chapter 2, presents a list of leadership actions and behaviours that were mentioned as useful for leaders of distributed teams, particularly to overcome the two challenges. Leadership in distributed teams was found typical in its active component. Five general focus areas for distributed team leadership were identified: (1) facilitating awareness, (2) developing an effective communication climate (3) motivating members, (4) formalizing and structuring and (5) focusing on the team as a whole. Chapter 3 presents the development of a research model. First, literature is discussed on the specific elements of the context of distributed teams and the extensive debate that has taken place. Research findings of the impact of team characteristics on team processes and outcomes are presented, followed by a presentation of theoretical concepts related to the two challenges derived from Study 1, i.e. the development of effective working relationships, and the development of shared understanding. In the third part of the chapter a research model is presented. It contains a number of hypotheses about the relationships between leadership approaches, i.e. transactional, transformational leadership and distance leadership, team processes, i.e. shared understanding and trust in the knowledge of team colleagues, and outcomes, i.e. team performance and innovative behaviour. The model displays associations between leadership and team outcomes, which are mediated by team processes. Two team characteristics, i.e. geographic dispersion and team members specialization, are expected to moderate the relationships of leadership with team processes. Chapter 4 reports study 2. This is a quantitative field study aimed to test the hypotheses presented in Chapter 3 in three steps: (1) the relationship between leadership behaviors, innovative behavior and team performance, (2) the mediating roles of shared understanding and trust in the knowledge of team colleagues in these associations and (3) the moderating roles of geographic distance and specialization in the association between leadership, shared understanding and trust in the knowledge of team colleagues. The study took place in 35 distributed teams which were working in innovative and technological disciplines. The teams originated from 8 different organizations involved in the (management of) development of technology. The study used mostly existing measurement scales for the variables under study. Aggregation of the individual level data to the team level was problematic for some variables and therefore most analyses were performed at the individual level. To test hypotheses, mediated and moderated regression analyses were performed, supported by SPSS. Results of this study provide support for transformational and distance leadership to influence team processes and outcomes in distributed teams. Shared understanding mediated the association of transformational and distance leadership with innovative behaviour and team performance. Partial mediation was found in most cases and full mediation occurred for the association between distance leadership and team performance. Trust in the knowledge of team colleagues was found to partially mediate the relationship between leadership styles and team performance, however, trust did not mediate the relationship of the leadership styles with innovative behaviour. Contrary to expectations, in study 2 no support was found for the moderating role of geographic distribution in associations of leadership with team processes, i.e. shared understanding, and trust in the knowledge of team colleagues. Specialization of knowledge was found to moderate the association of transformational leadership with shared understanding. In Chapter 5 theoretical and empirical findings are discussed and integrated. After an introduction, first the role of transformational leadership at a distance is discussed. Transformational leadership was found the strongest predictor of shared understanding, trust and team outcomes. Surprisingly, the degree of geographic dispersion did not moderate the impact of leadership on team processes, whereas a recent study by Joshi and colleagues (2009) did find this effect. Next, the importance of shared understanding and trust for team effectiveness is discussed. Shared understanding was found to be a challenge for distributed teams and to be an important mechanism to reach team performance. Surprisingly it received relatively little research attention in distributed teams. Some measurement issues are discussed, particularly in the case of field studies. The role of trust is important for team performance, but less important for innovative behaviour. Suggestions to develop shared understanding and trust in distributed teams are discussed. Next, the attention is focused to how distributed teams are (un)like conventional colocated teams. It is concluded that distributed teams are in many respects different from conventional teams, which renders these teams to be less ‘teamy’. Several team characteristics are discussed with regard to their effects on the ‘teamness’ of distributed teams, as well as several approaches to study the effects of these characteristics. Next, the practical implications of the studies reported in this dissertation are discussed in three areas, i.e. selection and development of team leaders, the role of face-to-face meetings and the use of ‘richer’ technology for development of shared understanding, and the characteristics to look for in members of distributed teams. Finally, a reflection on the results is presented followed by suggestions for further research in four domains, i.e. further exploring the effects of the distributed team context, further exploring and analysing the value of distance leadership behaviours, exploring the different domains of shared understanding, and investigating the development of shared understanding over time.