Work is an essential part of most people’s lives. With increasing flexibility in work life, many employees experience job insecurity – they perceive that the future of their jobs is uncertain. However, job insecurity is not just an individual experience; employees can perceive that there is a climate of job insecurity at their workplace as well, as people collectively worry about their jobs. The overall aim of this thesis was to investigate the job insecurity climate construct and how it relates to work- and health-related outcomes and to individual job insecurity. Three empirical studies were conducted to investigate this aim. Study I investigated the dimensionality of the job insecurity construct by developing and testing a measure of job insecurity climate − conceptualized as the individual’s perception of the job insecurity climate at work − in a sample of employees working in Sweden. The results indicated that individual job insecurity and job insecurity climate are separate but related constructs and that job insecurity climate was related to work- and health-related outcomes. Study II examined the effects of individual job insecurity and job insecurity climate on work- and health-related outcomes in a sample of employees working in a private sector company in Sweden. The results showed that perceiving higher levels of job insecurity climate than others in the workgroup was associated with poorer self-rated health and higher levels of burnout. Study III tested the relationship between individual job insecurity and job insecurity climate in a sample of Flemish employees. The results indicated that individual job insecurity is contagious, as individual job insecurity predicted perceptions of job insecurity climate six months later. In conclusion, by focusing on perceptions of the job insecurity climate, the present thesis introduces a new approach to job insecurity climate research, showing that employees can perceive a climate of job insecurity in addition to their own individual job insecurity and, also, that this perception of the job insecurity climate at work has negative consequences for individuals and organizations. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript.</p>