The Centre for Alternative Technology (CAT) (Welsh: Canolfan y Dechnoleg Amgen) is an eco-centre in Montgomeryshire, Powys, Wales dedicated to demonstrating and teaching sustainable development.

CAT also runs education programmes for schools and sells environmentally friendly items through its on-site shop, restaurant and mail order department.

CAT was founded by businessman-turned-environmentalist Gerard Morgan-Grenville, and opened in 1973 in the disused Llwyngwern slate quarry near Machynlleth (once served by the narrow-gauge Corris Railway), where it occupies a seven-acre (28,000 m2) site.

[2]: 14.39  Inspiration for the early CAT pioneers included the then-recent books Small Is Beautiful, A Blueprint for Survival, and The Limits to Growth[2]: 08.11  as well as an aim to explore alternative ways of living.

[5] The facilities and exhibits include: In 2023, the CAT announced that financial pressures had forced it to stop admitting walk-up day visitors, although it would continue to hold group visits and other events and courses.

The presence of the Centre in the Dyfi Valley has brought an increased environmental emphasis to the area, which is now designated as a UNESCO Biosphere Reserve.

An industrial estate (the Dyfi Eco Park) near Machynlleth railway station houses the offices of Dulas Ltd, a renewable-energy company founded by ex-CAT employees.