The book chapter analyses the long-term evolutions of the EU Internal Energy Market Policy, taking a historical-institutional approach with focus on shifts in coalitions supporting and opposing the idea of a free-market solution to European energy problems. It gives a brief historical description of policy development and analyses in greater detail the Third Internal Energy Market Policy Package adopted in 2009. Specific attention is given to the failure of getting adopted mandatory ownership unbundling of the transmission grid business. We identify the key stakeholders, their positions, and how these positions have changed or remained stable over time. Particular focus in the explanation is on the evolutions of the relative power of Member State governments and EU institutions, especially the Commission and the Parliament. The Chapter next evaluates progress in completing the EU internal energy market prosess and prospects for future policies in the field.