With the increasing use of mobile technologies in modern organisations, managers are facing the dilemma of having to manage the performance of individuals who are removed from their direct sphere of control, while using performance management principles that have not necessarily been adapted to accommodate this. The study investigated, analysed and described the management and measurement of the performance of these virtual knowledge workers from the perspective of the manager, with the aim of proposing a new conceptual framework to assist managers in this task. In addition, the study identified the organisational context and individual contribution required to support such a framework. The study used a constructivist grounded theory framework, with the aim of building theory through an inductive approach rather than testing existing theory. An embedded, multiple-case study research design was used to execute the study, comprising five companies in the Information and Communications Technology and related sectors in South Africa. Quantitative and qualitative data were collected at the organisational, team and individual levels. In total, 39 interviews were qualitatively analysed using content analysis aided by ATLAS.ti. The 163 questionnaires were quantitatively analysed using descriptive statistical methods. Thereafter, within-case and cross-case analyses were performed to extract themes and to propose a conceptual framework for the enablement of the performance of virtual knowledge workers. The research uncovered four key findings. The first finding was that the concept of "virtual" in the term virtual worker is often misunderstood, and that the definition should be applied on a continuum of virtuality, leading to the concept of perceived and true virtuality. The second finding was that true virtuality influences how performance is perceived, and how deliverables and metrics contribute to perceived, actual and true performance. The third finding was that parameters affecting virtual performance include organisational, contextual, and customer factors, as well as the managerial approach itself. The manager needs to become the mediator for these parameters, thereby fulfilling the role of enabler of virtual performance. The fourth finding was that the visual or face-to-face element still remains important when managing the performance of virtual knowledge workers. The study makes a significant contribution on a theoretical level by extending existing theoretical models regarding virtual distance and the management of dispersed teams into a much more comprehensive model. This concentric performance enablement model for virtual knowledge workers shows how the manager acts as enabler for the true performance of the virtual knowledge workers. On a methodological level, the research demonstrates how an embedded, multiple-case study, executed on three levels of analysis, and based on a grounded theory approach, can be executed to develop theoretical insights into the complex phenomenon of enabling the performance of virtual knowledge workers; and lastly the study has also made a contribution on the level of practice, by giving managers a conceptual framework and practical recommendations on how to manage and enable the performance of virtual knowledge workers.