This chapter analyses the implementation process of an ex ante community-based human rights impact assessment (HRIA) carried out in Mexico regarding a proposed gold-silver mine. The HRIA was conducted by a grassroots organization of community members affected by the mining exploration, accompanied by three civil society organizations. The chapter identifies good practices and areas of improvement for future assessments. It analyses if the HRIA followed a human-rights-based approach and fulfilled the essential elements of good practice. The discussion of the chapter focuses on the period from the beginning of the assessment (September 2014) to the presentation of the main findings in a final report (April 2016). The analysis highlights community participation and empowerment during the process, in particular noting the usefulness of innovative participatory approaches such as power mapping and collective social mapping. The chapter concludes by identifying improvement areas and giving recommendations to address them.