Negative symptoms in schizophrenia significantly impact quality of life and overall functioning. This chapter provides a comprehensive overview of clinical tools for assessing negative symptoms, encompassing hetero-assessments (evaluations based on observer ratings), self-assessments, and digital phenotyping. An examination of clinical trials from 2019 to 2024 reveals a diverse array of tools used to assess these symptoms, with the predominant choice being the negative subscale of the Positive and Negative Syndrome Scale (PANSS), which is not in line with the recent European Psychiatric Association recommendations. The disparity between recommended guidelines and actual clinical practices emphasizes the ongoing need for standardized approaches to ensure consistency and comparability in research outcomes. In essence, the chapter presents an evolutionary perspective on assessing negative symptoms in schizophrenia, advocating for an integrated approach that combines clinical observations with subjective experiences reported by patients and objective measures through digital phenotyping.