The Wales Act 1978 (c. 52) was an act of the Parliament of the United Kingdom intended to introduce a limited measure of self-government in Wales through the creation of a Welsh Assembly.

The act never took effect as a result of the "no" vote in 1979 Welsh devolution referendum and was repealed in 1979.

Had the Wales Act 1978 entered force, it would have created a Welsh Assembly without primary legislative or tax raising powers.

A Chairman of the Executive Committee would have been selected who would also be Leader of the Assembly.

The proposed assembly would have had responsibility for: The provisions of the Act were put to the populace in 1979 in a referendum held on 1 March 1979 through the question: The results of the referendum were: As a result of the negative referendum outcome, the Act never took effect, and was repealed in accordance with the Act's own provisions by the Wales Act 1978 (Repeal) Order 1979.