This historical overview explores the origins, subsequent development, and reinterpretations of the Curwen hand-signs from their nineteenth-century invention to their contemporary use. The gestures were devised by the English Congregational minister and educator John Curwen (1816-1880) and first published in 1870 as a technique to support his Tonic Sol-fa method. Curwen had begun developing his approach in the early 1840s after encountering Sarah Anna Glover’s (1786-1867) relative sol-fa system, and throughout his life he continued to refine and expand it. Drawing inspiration from Édouard Jue de Berneval’s shape notations and his concept of “mental effect” (sense of tonality), Curwen designed the “manual signs” as physical expressions of the “mental effects” of tones within a key to foster inner hearing and musical understanding.By the late nineteenth century, the hand-signs—integral to Curwen’s method—had been adopted in many countries and incorporated into a variety of pedagogical traditions, but also underwent changes both in shape and use. For instance, German music educator Fritz Jöde used the gestures not only as a sight-singing teaching technique but also as a tool for conducting mass singing during his open music lessons. Inspired by Jöde, Hungarian music educators adapted and further modified the Curwen gestures, and from the 1960s disseminated them globally. As a result, by the mid-twentieth century, the gestures had become most closely associated with Kodály-inspired music education. Even the “New Curwen Method,” which sought to update and reintroduce Curwen’s Tonic Sol-fa in Great Britain in the 1970s, reimported the hand-signs in their Hungarian-modified form. Later adaptors and practitioners highlight many benefits of using hand-signs (such as spatial and kinesthetic learning); however, the original intent—the expression of “mental effects”—is rarely mentioned.The history of the Curwen hand-signs illustrates how educational innovations travel, adapt, and acquire new meanings: from a nineteenth-century English invention aimed at embodying the tonal sense of sounds, they have become a globally recognised and continually reinterpreted practice, reshaped for new eras and new educational aims.