A national transport, health and environment action plan (NTHEAP) is a key mechanism for developing sustainable and healthy transport in a country. This manual was developed to guide NTHEAP development by countries. It proposes four phases: planning, development, implementation and evaluation. It does not provide specifics on how to establish general policies or strategies on sustainable and healthy transport, an activity that usually precedes the development of NTHEAPs. The manual provides practical advice on each of the phases (and the steps that comprise them) in an NTHEAP and highlights good practices from the European Region.