The aim of this thesis was to develop and test a theoretical model of fiendships in the workplace. Friendships within organisations may have a profound effect on an employee's experience of work, potentially either hindering or facilitating organisational functioning, yet friendships have seldom been studied in an organisational context. The association between friendships at work and organisational outcomes such as job satisfaction, organisational commitment and turnover intentions were investigated in three studies, assessing support for a theoretical model. In the first study, employees of a large Auckland hospital Waitemata District Health Board, Auckland (NZ) (n = 124) were surveyed using a written questionnaire. Results indicated that cohesiveness and opportunities for friendship were related to increased job satisfaction, leading to increased organisational commitment and decreased turnover intentions. The actual prevalence of friendships was primarily related to decreased turnover intentions. Overall there was good support for the proposed model. The need for further research to ascertain the generalisability of the findings was highlighted. A second study was conducted using an Internet based questionnaire, accessed both from within New Zealand and worldwide. A diverse sample of employees responded (n = 412). The analysis (structural equation modelling) indicated further support for most aspects of the model, suggesting that the findings are generalisable and the model is robust. The model of workplace relationships was cross-validated in a third study, confirming linkages between friendships at work and organisational outcomes. The model was then tested for intergroup invariance. The model was invariant across groups reporting differing needs for affiliation, autonomy and achievement, but non-invariant across groups occupying relatively less or more interdependent jobs. Results suggest that the interdependence of individuals' jobs affects the salience of work friendships more than respondents' subjective need. Overall, the research suggests that the presence of workplace friendships has a significant effect on several workplace variables, with the effect of friendships being more salient for individuals in interdependent work roles. The implications of the research findings are potentially far reaching. Not only do workplace friendships improve employees' experiences of work, but they also have the potential to affect the financial "bottom line" through factors such as enhanced organisational commitment, job satisfaction and reduced intentions to leave.