[Theory of change implemented in the program to promote physical activity "La Ribera Camina"].

Objective: To develop a theory of change of a program to promote physical activity in eleven health districts, in order to improve its design and plan its evaluation.

Method: Four focus groups were carried out, to develop a participatory theory of change, to identify the expected changes (long, medium and short term) of "La Ribera Camina" program, according to the following stakeholders: primary healthcare professionals, local government representatives and community members. A thematic analysis was used to identify the actions to be taken to achieve these changes, as well as the difficulties and facilitators to enhance the sustainability of the program.