Labour unions have been instrumental in the institution and maintenance of what many in the Western world would now consider basic business practices, from the forty-hour working week to stringent health and safety regulations. Despite their historical influence and contemporary resurgence in popularity evincing their importance to many members of the past, present, and future working class, unions are a disproportionately large blind spot in the industrial-organisational psychology literature. While several studies have found correlations between union membership or level of participation in one’s union and positive and negative economic, health, and psychological outcomes, we do not know how unions affect their members’ subjective sense of wellbeing. We also do not know who those members tend to be in terms of personality or sociopolitical characteristics—a significant oversight given the relationships between these individual differences, workplace outcomes, and wellbeing. This thesis sought to connect and address both gaps. Unionised (n = 307) and non-unionised (n = 162) academic staff from public secondary and tertiary schools in New Zealand (n = 287) and Australia (n = 182) were recruited via email to participate in an online survey from June 25th to September 14th, 2023. Unionised staff were further classified as casual (n = 152) or dedicated (n = 155) members, depending on their willingness to participate in union activities. The survey assessed union attitudes and beliefs (study-specific questions, Kelly and Kelly (1994) questionnaire, New Zealand Worker Representation & Participation Survey), personality characteristics (HEXACO-60, HEXACO Interstitial Altruism Scale, Goldberg’s (1999) 10-item International Personality Item Pool Representation of the NEO-PI-R Neuroticism Domain, Authenticity Scale), sociopolitical characteristics (Auckland Individualism-Collectivism Scale, study-specific questions), and global and domain-specific wellbeing (I COPPE). Two-way ANOVAs comparing total I COPPE scores between members and non-members, and casual and dedicated members, in Australia and New Zealand, found no statistically significant differences in wellbeing; notably, mean wellbeing scores were relatively high in all groups. Logistic regression models using demographics and personality and sociopolitical characteristics significantly predicted variance in union membership (member/non-member) and participation level (casual/dedicated) in New Zealand (22.50%, 25.00%) and Australia (28.20%, 48.70%); the individual differences that served as significant predictors were different in each of the four models. Finally, a linear regression model (collapsed between countries) using demographics, individual differences, and union membership significantly predicted variance in total global wellbeing (15.60%); union membership was not a significant predictor. Although union membership was not a significant correlate of wellbeing, most members and many non-members attributed improvements in working conditions and wellbeing to the influence of unions. We believe that, rather than having no significant beneficial or detrimental effect on wellbeing, unions positively affect the standards of the education industry holistically. Additionally, education unions seem to attract different people in different countries. It seems unlikely, then, that differences in the wellbeing of members can be attributed to correlations between individual differences and wellbeing. We conclude that future research should investigate wellbeing and individual differences in unions in different countries, industries, states of industrial relation, and time periods.