There is growing consensus on the need to consider and support markets as part of humanitarian responses. It is assumed that this support will increase the impact of responses - yet to date such assumptions are rarely supported by data and strong evidence. This evidence synthesis, commissioned by the Humanitarian Evidence Programme and carried out by a team of independent and multidisciplinary consultants, represents the first ever attempt to identify, synthesize and evaluate the existing evidence on the influence of market support interventions on household food security in humanitarian crises. It is accompanied by a stand-alone executive summary and evidence brief. It forms part of a series of humanitarian evidence syntheses and systematic reviews commissioned by the Humanitarian Evidence Programme.