Edinburgh's Telford College has started merger talks with the Stevenson and Jewel & Esk colleges in the city.
Telford had previously declines to get involved in the merger talks. However, Education Secretary Mike Russell has said the government should “force the pace” on college mergers.
Ministers said higher and further institutions must find more efficient and effective ways of working, especially in light of public spending cuts.
Telford College took the decision to join merger talks after a meeting of its management board. It said it will consult with students and other parties.
Jim Donaldson, chairman of Telford College, said: “All three Edinburgh colleges work collaboratively already, but we consider that the best way now to develop skills and learning opportunities, particularly for the city's school leavers and young people, is to work together to create a single, merged college for Edinburgh.”