Holy wells with miraculous healing qualities and resident supernatural beings are the focus of ritual and lore around the globe. Ireland’s holy wells include springs, lakes, and ponds with patron saints, specialized cures, and localized customs related to the site’s landscape setting. Deemed so foundational to Irish life and identity, holy wells were chosen in 1934 as the subject of Ireland’s first national folklore survey. Of the over 3000 holy wells documented on the island of Ireland, about a third are still visited or known; some attract international pilgrims and others are stewarded by a single family. While numerous wells have been lost to booming economic development in the last two decades, many remain sites of daily individual devotions and of annual gatherings to honor associated indigenous saints who were never officially canonized. Holy wells are not only irreplaceable resources of spiritual, archaeological and historical significance, they are also part of Ireland’s biocultural heritage. Wells and their landscape contexts are conservation patches for particular species of trees, plants, birds and pollinators. In this book, over 40 academics, heritage planners, and community researchers examine the Irish holy well tradition through the lenses of anthropology, archaeology, art history, biomedicine, folklore, geography, history and hydrology.