Continuing to be active in the Labour Party, Lamont became a prominent campaigner on issues related to social justice, equality and devolution. Although she had voted no in the 1979 referendum that proposed the establishment of a Scottish Assembly, during the 1980s and 1990s she was a representative on the Scottish Constitutional Convention, the body that paved the way for Scottish devolution. Of her 1979 decision, Lamont has said that she "came from the strand on the left which saw the politics of nationalism as a diversion from more central aims [but later] came to see the parliament as a vehicle for democratic change in Scotland." She was a member of the Scottish Executive Committee of the Labour Party, serving as chair in 1993.