The Centre for Alternative Technology (CAT) is an eco-centre in Montgomeryshire, Powys, Wales dedicated to demonstrating and teaching sustainable development. CAT, despite its name, no longer concentrates its efforts exclusively on alternative technology, but provides information on all aspects of sustainable living. It is open to visitors, offers postgraduate degrees as well as shorter residential and one day courses; and publishes information on renewable energy, sustainable architecture, organic farming, gardening, and sustainable living. CAT also runs education programmes for schools and sells environmentally friendly items through its on site shop, restaurant and mail order department.

Until 1974, Montgomeryshire was an administrative county in mid Wales, later classed as one of the thirteen historic counties of Wales. It was named after its county town, Montgomery, which in turn was named after one of William the Conqueror's main counsellors, Roger de Montgomerie, who was the 1st Earl of Shrewsbury.