This study uses nearly one million Tweets from eight campaigns targeting seven countries to explore the relationship between social media and domestic legal change, specifically in the area of women’s rights. The research is underpinned by a critique of the spiral model of human rights change and second wave normative scholarship. The study focuses on quantifying contextual, independent (online behaviours), and dependent variables (legal change) in order to model the effectiveness of campaigns. Using the space of social media presents a wide range of opportunities as well as threats. It may be that these campaigns are indeed leading to the change sought after by domestic women and girls, and that, as many posit, the weight of the international attention leads to positive outcomes. Equally, it may be that the campaigns are ineffective or, worse, lead to harmful government backlashes. This research seeks to understand these outcomes in depth, using empirical data to model the effectiveness of campaigns. This article in particular focusses on the methodological challenges and solutions with this kind of large-scale comparative social media research.