Femicide has become a mobilizing keyword for women and feminists worldwide. Drawing on digital activism and hashtag feminism literature, this chapter examines the case of the Argentinian #NiUnaMenos movement. Based on a quali-quantitative analysis, it accounts for how much and in what way femicide was discussed on Twitter during the mobilisations of the first three years. In 2015, femicide served to frame the broader problem of gender-based violence into the collective imaginary, with high rates of online engagement that brought the issue to national and international public attention. Over the next two years, the online discussion decreased but more bluntly denounced the femicides, humanizing the phenomenon with the names of the victims and emphasizing its public significance.