Why do people join trade unions?
Against the background of the general decline in union membership in Western countries, this study analyses factors influencing an individual’s choice whether to join a trade union. The focus is on the effects of workplace union density and individual political attitudes. Micro data covering the entire Danish workforce combined with European Social Survey data enable for the first time the statistical analysis of the effect workplace union density has on union recruitment. Workplace union density is used to measure the power of social custom in workplace union membership, constituting an instrumental motive for joining the union. Self-placement on a political left-right scale measures political attitude which is assumed to constitute a value-rational motive. The statistical results indicate that workplace union density is the main predictor of whether or not an employee is going to join a union, even when other variables such as gender, occupation and industry worked in are taken into consideration. In addition, the results indicate that political attitude is also an important factor.