"On Ilkla Mooar Baht 'at" (Standard English: On Ilkley Moor without a hat)[2] is a folk song from Yorkshire, England.

The song tells of a lover courting the object of his affections, Mary Jane, on Ilkley Moor without a hat (baht 'at).

Dr. Arnold Kellett reports the traditional belief that the song "came into being as a result of an incident that took place during a ramble and picnic on the moor.

[5] The first published version of the words appeared in 1916, when it was described as "a dialect song which, for at least two generations past, has been sung in all parts of the West Riding of Yorkshire".

[14] The American folklorist Helen Hartness Flanders recorded a version in her hometown of Springfield, Vermont[15] and another in Naushon Isle, Massachusetts[16] in the 1940s, suggesting that the song had made its way to North America with immigrants from Yorkshire.

A new musical rendition of on Ilkla Moor Baht'at was produced in 2013 by Grammy award winning artist Eliot Kennedy, featuring Lesley Garrett and Brian Blessed rapping the song.

[17][18][19][20] The project was the brainchild of Clair Challenor-Chadwick at Cause UK Public Relations, stemming from the idea that Yorkshire children didn't know the song.

The lyrics include many features of the Yorkshire dialect such as definite article reduction, H-dropping, and traditional second-person singular pronouns.