"Digital information and communications technologies like social media are critical for trade union renewal. Yet, although many unions now use social media, there remain ongoing debates as to what effective digital activism looks like. This question is even more pressing for the Global Unions, as international labour movement organizations without grassroots members. Drawing on social movement and networked communication theories, this article interrogates Global Unions' social media practices through a mixed-method analysis of 19,009 Facebook posts created between 2017 and 2022. Based on this analysis, we find that Global Unions that adopt crowd-focused communication styles and post on broader social issues have more success in engaging with online crowds than those that emphasize workplace or organizational issues and adopt top-down communication styles. At the same time, our findings challenge assumptions in the literature that crowd-led, connective communication styles associated with engagement are necessarily the most effective in today's digital society."

Support: Digital