Feminicidio is a Mexican adaptation of the radical feminist concept of femicide, usually defined as the misogynous murder of women by men because they are women. In this essay based on original fieldwork, I seek to contribute to Third World Approaches to International Law (TWAIL) scholarship by providing a brief analysis of the engagement of Mexican grassroots feminist activists with international human rights law in their struggle against the systematic abduction, murder, and sexual abuse of hundreds of women and girls in Ciudad Juárez, Mexico, and the widespread impunity enveloping these crimes. As a result of this grassroots activism, these murders became known as feminicidios. Feminicidio expanded the existing concept of femicide by exposing the complicity of the state in the killing of women by sustaining the institutionalization of gender inequality. Indeed, activists consistently claimed that the state’s tolerance for impunity perpetuates the notion that women are disposable, and violence against them is not serious. Moreover, they linked this notion to the patriarchal regime of neoliberal capitalism that supports the maquiladora industry in Ciudad Juárez. Activists further drew on international human rights law. They invoked the due diligence obligation to conceptualize the responsibility of the Mexican state for failing to effectively prevent, investigate, and punish the murder of women—despite evidence of a systematic pattern of gendered violence that could only be understood by taking into consideration the intersecting structural gender and class inequalities that feminicidio revealed.