SummaryThis paper updates a British Nutrition Foundation (BNF) Briefing Paper on this topic, published in 2011. Healthy eating and being physically active are particularly important for children and adolescents. This is because their nutrition and lifestyle influence their wellbeing, growth and development. There remains considerable room for improvement in the diets of British schoolchildren, according to findings of the government's National Diet and Nutrition Surveys (NDNS), but some improvements have been made in the past decade. Although intakes of saturated fatty acids and non‐milk extrinsic sugars have decreased in recent years, on average, they are still above recommended upper levels. Average contribution of fat to total energy intake has dropped below the recommended upper level of 35%, but fibre intakes remain low. With regard to micronutrients, many teenage girls are consuming low amounts of iron, but there is also evidence of low intakes of vitamin A, riboflavin, calcium, magnesium, potassium, selenium, iodine and zinc. New data on micronutrient status is now available for 11–18 year‐olds, and reveals low levels of vitamin D, riboflavin and iron (mainly in girls). Low vitamin D intake and status is a particular problem in some ethnic minority groups, especially South Asian children. There is also some evidence of socio‐economic inequalities; for example, children from families with higher incomes tend to have higher intakes of fruits and vegetables compared with children from families with lower incomes. This paper also discusses how dietary patterns can influence the micronutrient intake and status of schoolchildren, as well as the risk of overweight and obesity.Since publication of the Briefing Paper in 2011, new physical activity guidelines have been published and, for the first time, these are UK‐wide guidelines. Also for the first time, UK‐wide data on physical activity levels in schoolchildren are available (for 7‐year‐old children). Physical activity levels vary little between the UK regions, with the exception of Northern Ireland where fewer children meet the UK recommendations than in other regions. The data highlight significant differences between boys and girls (with girls generally being less active) and significant differences between ethnic groups. In particular, children from the Bangladeshi, Indian and Pakistani ethnic groups are less likely to meet the recommended levels of physical activity compared with other children.Obesity remains a major problem among British schoolchildren and there is a stark socio‐economic gradient, with levels of obesity being highest in the most socially deprived children.This paper also discusses various health issues in children, including iron deficiency anaemia, oral health, bone development, food allergy and intolerance, and cognitive function in children, updating the previous paper with the latest statistics and evidence.The findings of the NDNS serve to emphasise the importance of a whole school approach to good nutrition embracing the school curriculum as well as the food and drink available in schools (as highlighted in the recently published School Food Plan). School food provision has seen many changes over recent years, with school food standards now in place in all UK regions, most recently Wales. Various evaluations of the impact of school food standards, mainly in England, have highlighted improvements in the diets of schoolchildren, not only in the school setting but in their diets overall. However, there remains room for improvement. This paper also briefly describes a selection of initiatives and organisations of relevance to child nutrition.