By 2050, the Netherlands wants to reduce its use of natural gas for heating to zero. Currently, over 90%of houses are dependent on the fossil resource to warm their houses. As such, the phase-out of natural gas hasbecome an important policy project. The government delegated the formulation of the phase-out strategy andexecution to the 347 municipalities. This thesis examines how one municipality, Leiden, has formulated andimplemented this strategy. In doing so, the thesis addresses two matters in the literature on energy transitionswhich have received little attention: heating and deliberate decline. Traditionally, the focus within this field hasbeen on electricity and innovation. This thesis aims to find out to what extent the Transition Management (TM)framework by Derk Loorbach (2010) can be applied as a guide to a phase-out policy formulation process of theWarmtevisie of the Dutch municipality of Leiden. The thesis uses the process tracing methodology to combinedata generated from document analysis and two interviews with policy makers involved in the policy formulationprocess. By comparing the process followed in Leiden with the analytical framework of TM, the thesis shows thatthe TM framework could be used to guide to the phase-out policy formulation process to a large extent. However,the case study also shows that knowledge and expertise must increase substantially for a sound strategy to emerge.Additionally, it shows that even within phase-out strategies the focus remains on innovation practises.