This thesis investigates workplace cyberbullying, defined as a situation where over time, an individual is repeatedly subjected to perceived negative acts conducted through technology (for example, phone, email, web sites, social media) which are related to their work context. In this situation the target of workplace cyberbullying has difficulty defending him or herself against these actions. The thesis has two broad aims: (1) to develop a workplace cyberbullying measurement scale; and (2) to investigate the impact of workplace cyberbullying on employees. Workplace cyberbullying is conceptualised in this thesis by drawing on the traditional workplace bullying and cyberbullying literature. A rationale is presented for investigating it as a distinct form of workplace bullying and four separate studies address the development of the workplace cyberbullying measure (WCM). The first study generated measurement items by asking employees to describe cyberbullying behaviours. The behaviours were sorted into categories using content analysis and converted into measurement items. In the second study, the relative severity of each item was assessed so that the measure could be weighted according to severity. In the third study, the 34 item WCM was completed by a sample of 424 employees. A two factor structure (comprising work-related cyberbullying and person-related cyberbullying) was compared to a unidimensional factor structure and the measure was refined into a 17 item instrument. During the fourth study the nomological network of the WCM was constructed and further reliability and validity evidence was obtained. The fifth and final study then used the WCM to investigate the impact of workplace cyberbullying within a theoretical framework. The theoretical and practical contributions of the studies are discussed along with directions for future research.