Nowadays, pain is still one of the most urgent problems, and is an important factor for the need of medical assistance. Daily activity can be considered an index of the state of health, quality of life, and wellbeing of patients that suffer with chronic pain. In this study an instrument is shown which allows the assessment of daily functioning and impairment in this kind of patients (IFI: Impairment and Functioning Inventory). Subjects for this study were 135 patients with chronic benign and oncology pain associated with different pathologies (arthritis, back pain, neuralgia, fibromialgia, cancer). The final instrument has 19 items grouped into four scales: in and outdoor activities, independent functioning, and social and leisure activities. An exploratory factorial analysis with Varimax Rotation revealed that items were grouped into the four factors mentioned and obtained an adequate reliability index.