Globally, more than a quarter of children under the age of five years are stunted (undernourished). Stunted children experience lifelong problems with their health and are more likely to die early. The time at which an infant transitions from receiving only breastmilk to needing additional foods (complementary feeding) has been shown to be associated with increasing problems with stunting. Currently only 22% of Kenyan and 8% of Malawian children aged 6-23 months receive the minimum acceptable diet, down from 39% (Kenya) and 19% (Malawi) between 2008 and 2014. It is estimated that interventions which promote optimal infant and young child feeding (IYCF) practices could prevent 20% of deaths in under-fives in countries with high levels of child deaths. Approximately one-third of urban residents in low and middle income countries live in slums, with an additional 100,000 moving in daily. Children living in slums are more likely to suffer from under-nutrition than other urban children. Nevertheless the literature tells us that there is a lack of evidence regarding nutrition interventions in slum environments, and almost no evidence regarding the potential for 'nutrition-sensitive' interventions that target the drivers of poor nutrition such as poverty, cultural and social practices, and poor physical environments. Successful design of these types of intervention requires a well-integrated interdisciplinary approach. In addition to nutrition expertise, contributions from other disciplines are needed to understand the cultural, social, physical and economic environments that influence IYCF practices. We therefore propose an interdisciplinary network with the aim to produce evidence to drive future research and inform policies to improve the nutritional status of IYC living in poverty in sub-Saharan African countries (SSA) experiencing rapid urbanisation. The network is led by Loughborough University with Kenyan partners at the African Population and Health Research Centre and Malawian partners at the University of Malawi and The Lilongwe University of Agriculture and Natural Resources as well as UK partners at The Universities of Sheffield and Southampton. The specific network objectives will be to: 1) Prepare a rapid review of evidence documenting interventions for the urban poor to improve the nutrition of IYC in SSA; 2) Convene the first network workshop (to include stakeholders) to firstly guide analysis of existing data sources on this topic, to secondly consider the current evidence base and policies identified in the rapid review and finally to ask key stakeholders to identify highest-ranking evidence/research gaps for improving IYC feeding programmes and policies; 3) Undertake analyses of existing data from demographic and health surveys in sub-Saharan Africa and pre-existing data from slums in Nairobi to explore how the various drivers of IYCF practices are influenced by urbanisation and to consider whether those drivers vary for the urban poor compared to other urban populations; and finally 4) Facilitate end-of-project workshops to develop research proposals informed by evidence from the first three objectives and to present findings of the secondary analysis and discuss these with stakeholders (including Ministries of Health, NGOs, communities) and policy-makers. The network will also foster the development of skills in data analysis and evidence synthesis in early career researchers in the UK, Malawi and Kenya, thus helping to ensure a sustainable group with potential for evolving future leadership. In the longer term we will develop a UK-Africa interdisciplinary network with expertise to support interventions to promote optimal IYCF practices in rapidly urbanising environments. It is envisaged that such interventions will improve the human capital of developing countries by reducing under nutrition, thus promoting optimal cognitive and physical development, and thereby increasing prospects for economic prosperity.