Clouds House, also known simply as Clouds, is a Grade II* listed building at East Knoyle in Wiltshire, England. Designed by Arts and Crafts architect Philip Webb for Percy Wyndham and his wife Madeline, it was first completed in 1886, but an 1889 fire necessitated its rebuilding, finished in 1891. Clouds was Webb's grandest design. It became a centre of social activity for the intellectual group known as The Souls, and was frequented by artists such as Edward Burne-Jones and politicians like Arthur Balfour.
Since 1983 the house has been a treatment centre for drug dependence and alcohol dependence, under the name Clouds House. In 2007 the Clouds House treatment centre merged with two other organisations to form the charity Action on Addiction, which is headquartered at East Knoyle.
Wyndham bought the 4,207 acres (1,703 ha) Clouds estate in 1876, for c. £100,000. It was so-called because its lands included the former manor of Clouds, in Milton, Wiltshire, which was owned by John Clouds at some time before 1551.
Wyndham commissioned Webb to replace a smaller house on the site, at the head of a valley sloping down to the south-east, with uncultivated land lying to the north. It was Webb's grandest country house design, intended to facilitate the Wyndhams' continual round of house parties, creating "a palace of week-ending for our politicians" in the words of Webb's friend William Lethaby. Two south-facing drawing rooms were connected by double doors, allowing them to be joined into one large space. The south elevation, which had three gables, also featured a large balcony with a canvas awning, built over a loggia. It overlooked a terrace for outside dancing.