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The modified Rankin Scale (mRS), which measures the degree of disability or dependence in daily activities after a stroke, serves as the primary endpoint in most acute stroke clinical trials. Its simplicity, strong validity for stroke outcomes, and reliable inter-rater agreement—particularly when a structured assessment is used—have contributed to its widespread adoption. Developed in 1957 by John Rankin (1923–1981), the original 5-grade scale assessed functional recovery in patients with stroke, ranging from grade 1 (no significant disability) to grade 5 (severe disability).1 The scale was modified to its current 7-grade form by Warlow and colleagues for use in the United Kingdom Transient Ischemic Attack (UK-TIA) trial in the 1980s, with the addition of the extreme grades of 0 for no symptoms at all and 6 for death.2