This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To assess the effectiveness of social network and social support interventions to support cardiac rehabilitation and secondary prevention in the management of people with heart disease. As a secondary output of this review, and to assist in conceptualising future research focused on social network and social support interventions, we aim to develop a logic model theorising the relationship between social networks or social support and heart disease outcomes. We will draw on existing models of social support for health (e.g. Berkman 2000), as well as established approaches to theorising and implementing behaviour change (e.g. Michie 2011).