The few available studies of programme effectiveness in nutrition find that programmes are less effective than would be predicted from the efficacy trials that are the basis for evidence‐based programming. Some of these are due to gaps in utilisation within households. To a greater extent, these gaps can be attributed to problems in programme design and implementation. ‘Implementation research in nutrition’ is an emerging area of study aimed at addressing this problem, by building an evidence base and a sound theory to design and implement programmes that will effectively deliver nutrition interventions. The purpose of this supplement to Maternal & Child Nutrition is to contribute to this growing area of implementation research. The series of papers presented and the reflections for policymaking and programmes, combined with the reflections on the application of ethnography to this area of inquiry, illustrate the value of systematic research undertaken for the purpose of supporting the design of nutrition interventions that are appropriate for the specific populations in which they are undertaken. © 2015 Blackwell Publishing Ltd