The traditional Welsh costume is a costume once worn by rural women in Wales. It was identified as being different from that worn by the rural women of England by many of the English visitors who toured Wales during the late 18th and early 19th centuries. It is very likely that what they wore was a survival of a pan-European costume worn by working rural women. This included a version of the bedgown, originally worn by the gentry in the 17th and 18th centuries, an item of clothing that survived in Wales for longer than elsewhere in Britain. The unique Welsh hat, which first made its appearance in the 1830s, was used as an icon of Wales from the 1840s.
It is likely that the Welsh costume began as a rural costume (with regional variations within Wales) and became recognised as a traditional costume by the wives and daughters of the better-off farmers, who wore it for special occasions and when going to market to sell their produce.
From the 1880s, when the traditional costume had gone out of general use, selected elements of it became adopted as a National Costume. From then on it was worn by women at events such as Royal visits, by choirs, at church and chapel, for photographs and occasionally at eisteddfodau. It was first worn by girls as a celebration on Saint David's Day just before the First World War. The costume is now recognised as the national dress of Wales.
Very little evidence for traditional Welsh costume survives before about 1770 when the first tourists came to Wales and recorded in words and pictures the costumes worn by women in Wales. They noted that the women in rural parts of Wales wore a distinctive costume which varied from place to place. Women in towns and those who lived near the Welsh-English border or near busy ports were already wearing English fashions, often made of cotton.
During the 1830s, certain members of the gentry, especially Augusta Hall (later Lady Llanover) of Llanover near Abergavenny, recorded and tried to preserve some Welsh traditions, including costume. The prints of costumes of parts of Wales which she may have commissioned did not have a wide distribution. Some of them were published in an article in 1951. This was the first time that they were published since the 1830s Her apparent influence on Welsh costume was greatly exaggerated following the publication in 1963 of an article on Welsh Peasant costume and this caused the general misapprehension that she was responsible for either inventing or preserving traditional Welsh costume. From then on, many writers assumed that she had a great influence on the wearing of Welsh costume by rural women throughout Wales during the 19th century, which, it was supposed, led to the creation of a National Costume but there is very little evidence for this.